I owned a Chevette that we swapped in a Bowtie common pin Brodix head 4.3.Ran 10.90's on the stop like clock work.All was a result of the comic book "Hot Rod"
article that stated Don Hardy had built one.Well they tried and decided it was too hard to mass produce.After I had thousands invested and called them for the headers I found that out.

These 4.3's follow the same formula.Ya want to build something different??.It's going to cost a lot more.............

If you want to do something simple with the 4.3's (not the reverse rotation ones),follow the marine builds for them and you can get some reasonable output.

BTW-I am having a hard time accepting the fact of a blown 4.3 putting out 500hp without it being very,very,close to not being street able.That is just a little short of 2hp per c.i.and on stock heads???.