Cheapo 400 hp build.....
350 SBC L31 heads
Flat tappet hydraulic cam, stock self aligning (SA) rockers, some head work for better springs.
In this build, a tight budget is called for. To that end, use stock self aligning rockers. Lift is under a half inch, so the SA rockers should be OK. Check to see if using a -0.050" lock will be needed to insure the valve tip sticks up far enough above the retainer so that the retainer top surface doesn't get loaded by the side rails of the rail rockers. More info on checking clearances, etc. under Resources.
Bore the block 0.030", use these or similar 12cc dished pistons w/5.7 rods.
Makes 9.6:1 static compression ratio. Cut block decks to zero and use a ~0.041" head gasket. The default gasket to use with aluminum heads is Fel-Pro 1003....
Fel-Pro Performance Head Gaskets Q1003 - SummitRacing.com
Makes a squish of 0.041".
Use XE274H Comp cam, installed straight up.
Comp p/n 981 valve springs, p/n 750-16 retainers, p/n 630-16 keepers and stock 1.5 rail rockers. 1.250" springs should be OK because the cam is a moderate grind, hydraulic flat tappet.
Machine the OD of the guide bosses to less than the I.D. of the damper spring and cut for PC-type positive seals.
Cut top of guide for 0.550" play from bottom of retainer to top of guide seal. Pin the pressed-in rocker studs with this kit.
Performance Distributors custom curved HEI distributor, p/n 12720, or build your own from a GM HEI.
Edelbrock RPM Vortec intake mounting a 750 vacuum secondary carb of your choice. Edelbrock, Rochester 5 psi max at the inlet, Holley 6 psi max at the inlet.
Performer RPM Vortec w/natural finish: p/n 7116, w/EnduraShine finish: p/n 71164, w/polished finish: p/n 71161, or look for a used manifold on craigslist to save a few shekels.
Long-tube 1-5/8" headers with X or H pipe right after the collectors, 2-1/2" to 3" pipes to the rear through mufflers of your choice.
Use 2500 stall converter, shorter rear gears.
RPM HP TQ
2000 138 364
2500 176 369
3000 224 392
3500 281 421
4000 331 435
4500 370 432
5000 402 422
5500 405 386
6000 375 328
Peak dynamic compression ratio 8.16:1 on KB's calculator.
Peak volumetric efficiency 97.2% @5000