The cam, and compression are a little low to meet the hp goal you are shooting for. I run a 383 (.040" =385) with a solid roller cam with 255/261° at .050 and .600/.620" with 1.6 rockers, 11.2:1 compression with DART pro 1 215 heads with a fair amount of work done to them, single plane intake, I have both an 850 and a 750 (that's had a bunch of work done to it) double pumpers that i use on it. I had the motor dyno tested before i put it back into the car and i got just over 560hp. As AP mentioned I have the 6.0" rods.
with that cam and the current compression I would say you are in the 500hp range (which aint to shabby)
Now about the comments about the split duration/ dual pattern cams: many cams you see will have a dual pattern on them, this is largely due to heads with poorer flowing exhaust ports. The AFR heads you have do have good exhuast ports so a dual pattern cam is not really of any benefit. At the same time I dont think it's going to hurt anything either.
About what Vinnie is saying, there is never any true replacement for cubic inch displacement, but at the same time you have to be willing to spend the extra 2000-3000 on the parts. Really no 434's are build on OEM cast blocks, and rarely do you find in the DART SHP block, normally they are done on the more expensive aftermarket blocks like the LittleM which is going to run you around 2200.00 then another 200.00 to get it delivered to you. Most rotating assy for the 434 will cost a few hundred more than a 383 rotating assy of the same caliber.
I certainly can't knock Vinnie cause I have wanted to build a 421 SBC for a long time now but I have a hard time spending that much money for block.
Last edited by my87Z; 10-05-2012 at 10:29 AM.