1973 340, want more power.

I always question when people toss out a pure HP number. If you define what you are really looking for, people on here can give you better guidance.

For example, do you simply want 450 hp or do you want a street-able 11 second car?

For that matter, do street manners even matter? We don't know from your post.

Chassis improvements are an important part of building a fast car? Does that matter to you or do you just want a pure HP number?