I squeezed a dyno tested 161 HP out of mine. The guys at the machine shop used a book by Dave Vizard, (ISBN 0 86343 0856), as a guide to do the head work, Esslinger roller cam, flat top pistons w/valve reliefs, 9:5 compression ratio, Schoenfield headers w/3" collector, Offy 2bbl intake w/Holley 500 2bbl carb.
If you decide on the headers, you will have issues regarding the passenger motor mount as Pintony has mentioned in other posts, but nothing that can't be resolved.
The head will cost you but so won't any other if done by a machine shop. Mine said that my application is good to 7000 RPM and that it was strongest from 6000 to 7000.
Not saying that this is the way to go, just what I did.
I know the overwhelming project issue, I'm up to my neck with two at present.
Al