There's a website that goes somewhat into detail about a HEI conversion for a Stovebolt distributor, but I can't in good conscience recommend it to anyone. The author has "borrowed" heavily from information I gave him, without attribution, and presented it as his own research. I'm working on a way to install a GM pickup coil and reluctor in an OEM distributor, and locate the module elsewhere, but I don't have a working prototype. When (if) that happens, I will gladly share the results of my research without trying to profit from it.
I believe a Carter YF carburetor designed for an AMC/Jeep 232 cubic inch inline six from the mid-1960s should be compatible with a Chevy 235, and those carburetors were manufactured around 20 years later than the Rochester B. I see "rebuildable cores" on Ebay pretty frequently, at fairly reasonable prices.
Jerry
