437 Cubic Inch Small Block

A 400 block with a 0.030" overbore and a 4.000" crank makes a 434. A 0.040" overbore and a 4.000" crank makes a 436. Maybe he's figuring a 436 plus wear :LOL:
http://speedomotive.com/ps-536-86-42...roker-kit.aspx

You can go to 455 with an aftermarket tall deck block and 4.125" crank.
http://speedomotive.com/ps-540-86-45...roker-kit.aspx

Here's the GM block to go 455....

22551790 Cast Iron Rocket Block (Tall w/Wet Sump)
This cast iron block is precision machined and does not require additional "blueprinting" to correct production tolerances. All block dimensions are machined to +/- .001". The block's extra-thick siamesed cylinder walls provide a minimum .275" wall thickness with a 4.125" bore. The cylinders can be bored to a maximum of 4.155" diameter. This block also uses the standard GM small-block V8's 4.400" cylinder bore centerlines. The outer water jacket walls are scalloped to enhance coolant flow around the siamesed cylinders. This block is available with deck height 9.325" (.300" taller than production). The reinforced deck has a minimum .625" deck thickness, regardless of the deck height specified. The head bolt holes are blind-tapped and the head bolt bosses are freestanding to minimize cylinder bore distortion. The three steel 4-bolt center main bearing caps have splayed outer bolts. The 2-bolt front and rear bearing caps are retained with studs. Blocks with standard deck heights use 2.45" main bearings; tall deck height blocks use 2.65" main bearings. This block uses a pre- 1985 two-piece small-block rear main bearing seal. Compared to a production small-block V8, the Rocket block's camshaft is raised .390" (4.912" camshaft-to-crankshaft centerlines). This relocated camshaft will clear a 4.125" stroke crankshaft without interference, eliminating the need for a small base circle cam when using a long-stroke crankshaft. This block uses big- block V8 cam bearings. These larger cam journals allow the camshaft base circle diameter to be enlarged, which enhances camshaft strength and reliability. The lubrication system has been revised. This block has a "priority main" lubricating system that directs oil to the main bearings before the cam bearings. The main oil gallery is located next to the camshaft tunnel: oil can be pumped into this gallery through a boss above the timing chain cover or through the bellhousing flange behind the #7 cylinder. In wet sump versions, the rear main bearing cap is machined for a standard oil pump. The oil pan rails are spread .800" (.400" per side) compared to a production small-block V8. These pan rails will clear up to a 4.125" stroke crankshaft in tall deck blocks with minor modifications. Other additions to this block are: dual starter mounts, production bosses for side and front engine mounts, and provisions for a block-mounted mechanical fuel pump.

Part Number.....22551790
Deck Height......9.325" (tall)
Oiling System...Wet Sump
Main Bearings...2.65" (400 type)
Bore Diameter...4.125"-4.190"
Technical Notes: Depending on components used, bottom of bores and oil pan rails may require notching and additional machine work for connecting rod and counterweight clearance. Mounting the starter on the left (driver's) side of the block provides additional clearance for an extended oil pan. If the block-mounted oil filter is eliminated, a remote filter is required.
http://www.sdpc2000.com/product/2255...cketBlock.aspx