Cost of an engine rebuild to obtain more power unsupercharged

[Alan]

Agree with Charles ( not unusual). While I was at it I'd get the tappet blocks re ground to 2 inch radius, but really 30bhp isn't about what you do to the engine, it's about getting the inlet and exhaust manifolds working properly. All the bits you need are available probably off the shelf, but you need a good strong basic engine and that costs roughly the same whether it's tuned or not. Of course, 40hp and the whole game changes.