400-425 is a lot of N/A horsepower from 302 cubic inches.
Anyways, AFR 185's or a well ported set of aluminum heads, 10:1 or more compression, a custom cam (forget about making 400hp N/A with an E303 cam), vic jr intake and a Biggs 650 Holley, 1 3/4" headers and a boatload of other stuff to tie it all together. You'll probably need a pro to set it up to get the results you want out of it.
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393W: AFR 205's, hydraulic roller, TKO600.
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