The early cranks can be rifle drilled as well. Not sure which is more economical - fixing the thrust geometry to accept a later model crank - or drilling an old crank already in hand.
My hopped up '49 stovebolt is running a '52 Powerglide crank with insert rod bearings and stock jet oiling. The Ross pop-up pistons provide 8.5:1 compression and at .030 over the engine is technically a 230. The red-line is roughly 4 grand. The stock heads quickly run out of flow at this point. Alas, the jet oiling system is enough given the useful RPM range.
Add a 12 port cross flow head and now the rod bearings become limiting . . .
