For deep pocket$..Lotus, anything Cosworth, or Coventry Climax
gotta love that name.
The Pinto OHC 4's have a boat load of after market stuff.
I love 70's Datsuns but the 2000 Fair Lady engine falls short. Any of the L-series 4 cyl.engines is the way to go.
They are a Z-series engine but as a 4, so there is gobs of gear for them.
The early Toyota 4's are Ok, but the Datsun, properly done will out do em'.
Alfa Rameo 4'$
Nice exhaust note :music:
BMW 1600 or 2002, the 72'tii is tits.
VW, some of the early 4's could be made to go, but suffer head gasket problems and a very crowded port face (thats where there is very little gasket surface between ports.
VW flat fours are fun to do but I want OHC if not DOHC and that takes us to Por$che
Get this book..ISBN 0-8376-0140-1, Phillip H. Smith is the MAN, when it comes to small/hi-output, older engines.
EDIT: Check Austrailian websites for hot-rodding small engines. The guys in OZ are like the USA was in the 60's & 70's,
when it comes to building small hi-output motors. Some out-fits down-under are making really sweet cylinder heads
to retro-fit older engines. Horsepower is in the port and combustion chamber design.