You can probably gain 200 to 250 hp with a simple,cheap engine.
If the cam is a hydraulic lifter CJ type it isn't going to rev over 6,500 no matter how light the valve train is.
All you need to make 450-500hp is a stock short block with flat top pistons, a set of ported 2v closed chamber Australian iron heads (cheap), and an aggressive, rumpity, rumpity hydraulic lifter cam with the right springs.
You can probably use your stock short block, even if it has dished pistons, spend $2,500 and be over 450hp.
You will be happier and live longer if you do it. Why wait?
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