I think you could make a 235 sing if you bought the right parts. If I remember right, the connecting rods have the big end the same as a Chevy small block. The length is pretty long though. But you can get some long rods for a SBC. Might have to buy 2 extra ones though. Well worth it for some nice strong forged rods. Still, the compression height wouldn't be exactly the same. That shouldn't stop you. Order some custom slugs from anyone that makes them forged, and the compression height can be adjusted.
I believe Sanducci even solved the weak main problem. He studded his mains and put an additional strap across the top.
For the head, someone makes an aluminum cross flow head for those. I don't remember who. But if worse comes to worse, you can adapt small block Chevy heads to work too. I've seen that done. You have to cut the last cylinder off each head and weld them together. Isn't that what Sanducci did too?
Then, why can't you run big boost and 5000+ rpm on a 235?
Rule of thumb is, if you can do 2 atmospheres of boost (1 atmosphere to bring it to manifold pressure of zero and 1 atmosphere to get it up to 14.7 psi), then you'll be making approximately 2 hp per cubic inch. That's 470 hp, folks. From a single turbocharger.
It's not going to be the cheapest rebuild option, but it will probably be the trickest.
