Let's go back to square one.

First off, I have heard some bad juju from professional engine builders concerning the Eagle kits. If I were doing this build, I'd start with a Scat cast steel crank kit with Scat I-beam 5.700" rods.

I'd also be starting with a roller tappet, one-piece seal block. It just makes no sense in this day and age to begin your build with a flat tappet block and have to worry about wiping the cam out due to lack of extreme pressure lubricants in the oils that are available today. There are tons of these blocks and even complete builder motors in the boneyards. Chevy began using rollers in 1987 in cars and I think about 1992 in trucks. If you could find a complete L31 5700 Vortec builder motor from a '96 to '98 Chevy truck, you would also get the L31 Vortec heads on it. These are the best production heads that Chevy ever produced and will outflow many aftermarket heads.

A Scat stroker kit in this L31 motor would make a dandy street/strip motor, using an RPM Vortec manifold and 750 vacuum secondaries carb, along with 1 3/4" long-tube, equal-length headers and a cam to match the SCR.

The Vortec heads are lift-limited to about 0.450" as produced stock because of retainer/seal interference. You can run more cam by either cutting the height of the valve guide boss and dropping the seal down, or you can upgrade the valve springs/retainers to CompCam beehives that will clear with more lift. I would opt for the spring/retainer change, because that way, you can run the springs recommended by the cam grinder for the cam you choose. Nothing more need to be done to the heads to produce good power on pump gas. If looking for the heads in a boneyard, look for a sawtooth design on the ends of the heads, then pull a valve cover and look for casting number 12558062. There's nothing wrong with using the rail rockers that come on these heads either. They'll work fine with moderate spring pressures without pinning the studs.

Using these pistons....
http://kb-silvolite.com/performance....etails&P_id=94
with the 64cc Vortec heads will produce 10.3:1 static compression ratio. Using this cam...
CompCams HYDRAULIC ROLLER-Great for street machines. Best with headers and aluminum intake. Use 2500+ stall converter. Rough idle. 2500 to 6000 08-450-8 286HR 286 286 230 230 .560 .560 110°
will produce these numbers.....
RPM HP TQ
2000 145 382
2500 184 386
3000 236 414
3500 300 450
4000 359 472
4500 406 475
5000 444 467
5500 450 431
6000 427 373

All I'm saying here is that by starting with a production motor and using selected parts to build it, you can have a motor that produces 450 horsepower and 475 ft/lbs of torque without expensive aftermarket heads. I might expect to pay $400 to $500 for a complete L31 builder motor, but not having to spend money on heads makes this the deal of the century.