We're stuck with a stock cam, rockers, pistons and cylinders. Single port heads, which can be ported slightly. Stock manifold, massaged, with a 28mm PCI carb(36hp flows better than 40 hp carb), 7.3:1 compression and stock size chambers. We can change valve springs as long as they're single, and change cam timing. But mostly stock. We're making right around 60 hp at that, with no fan and no generator needed.
Seriously, if you made 63 hp you'd have a real advantage.