Welcome to CHR!

You may want to see a parallel thread that advocates a BBC which is a sure bet for 400+ horsepower and when all said and done may be a good choice. I've always built small blocks but we have some great BBC guys here (Pat McCarthy is the world's best!). In that you have already bought a 350, here's my two cents on a 383 build and a few tips that I’ve continued to use for over 40 years with a proven combination of off-the-shelf components that will net you well over 450 horsepower and 460 plus foot pounds of torque.

As a side note: If you’re going to run this with an automatic my choice would be a well built 200R4 as it’s nearly identical to the TH350 and you can use your existing drive shaft. You could also use a 700R4 – your choice really – with the key being well built. Both transmissions have a low first gear and overdrive to give the 383 a nice launch as well as decent street manners even on the freeway (stay with 3:90 gears in the rear end and shoot for tires with a 30” - 33” diameter, 285/60-18 would be perfect). In either case, go with a 2500-2700RPM stall converter.

The components I have listed below are flat tappet, but you could certainly substitute a roller cam (with similar characteristics) and valve train if your budget allows such.

First and foremost – find a good machine shop where you can talk to the technician who will be doing the work. The prep on your block is critical. The 383 can be a screamer if built correctly, but heaven help you if clearances are not correct as the whole thing will come apart and you’ll have one very expensive door stop! Make sure that the technician has built many 383 motors. I know everyone has to learn somewhere – but you don’t want it to be your engine. The block doesn’t have to be a four bolt unless you’re going to race it real hard.

That said – have the block cleaned and tested – no need to build a block that has cracks or cannot be squared. Make sure that the machine shop understands that you’ll be building a screamer and that you want to have the crank journals align bored and the decks cut to 9.003” – this is an important measurement!! Have the machine shop install new cam bearings and new brass freeze plugs. Also have the machinist go over the location of all the galley plugs with you so you know where they are and that they have been properly installed. When you get the block back from the machine shop make sure you really scrub that baby down with hot soapy water. I like Dawn dish washing liquid and water straight from the bottom of the water heater. Put the block on the engine stand and dry with compressed air really well. Make sure you have a 55 degree or warmer day and paint the inside of the engine. I use Glyptal. Its $50 a quart from Eastwood – buy the brush on (versus aerosol) - a quart will do the job real nice (I use the disposable “China” bristle brushes from Harbor Freight). Also paint the exterior at this time too. Let everything dry real well – at least 48 hours, preferably in a warm garage.

Rotating assemblies are really your choice. Eagle makes a kit that includes crank, flexplate, damper, rods, bearings, pistons and rings for about $850. Part number from Summit is ESP-B13005E030. It’s probably fine for your application – uses a -7cc flat top and with the deck height recommended (remember that 9.003” measurement?) above should keep you in the 10-10.5:1 compression ratio with a .041 head gasket (see below for part number). Have your machinist press the pistons and rods together – it’s a bit tricky if you’ve not done it a lot and you need a press.

Use lots of good assembly lube (I like Red Line – carry over from old two stroke days!). Keep your hands really clean and wipe thing as you go (remember I told you to paint the engine? Lot’s easier to keep nice and clean with fresh paint inside and out!)

Oil pan assembly – Milodon 30901 fits stroker motors – might need a bit of adjustment with Eagle rods. Use Milodon 18750 oil pump with a 18314 pickup. Use Milodon 23050 oil pump drive shaft and 41000 one piece gasket (some may disagree – but I’ve never had an issue with the one piece when installed as a part of the original build when the engine is on a stand).. Milodon 81300 is an oil pan stud bolt kit – worth the $20 for ease of assembly.

Top the engine off with the components listed below:
AFR 1040 195 Street Eliminator heads
Double roller timing set - Summit is fine
Comp Cams 7972-16 chrome moly 5/16-inch pushrods
Comp Cams 812-16 lifters
Comp Cams 1305-16 Pro Magnum Roller rockers 1.60
Comp Cams 12-250-3 Xtreme Energy hydraulic cam XE284H - Duration @ 0.050": 240° / 246°, .507" / .510" lift
Edelbrock 2975 Victor Jr. intake manifold with a Demon 5402010 Mighty Demon 850 Carburetor
(Alternately, en Edelbrock Performer RPM and 750 carburetor will save a couple hundred dollars)
Fel-Pro 1205 intake manifold gasket
Fel-Pro 1003 head gasket
HEI Ignition - stock Chevy is a good unit - pair with a MSD ignition (stay away from Accel anything – my opinion)

Stop working when you get tired and you’ll save the headache of having to redo something. I still keep a log sheet on an engine and note everything I’ve done before I quit for the day – of late I’ve started taking pictures with a digital camera then have a visual record as well. It makes it a whole lot easier to ‘take-up-where-I-left-off, especially if there are a couple days between working the engine.

Have Fun,
Glenn