Any engine builder with a few brain cells to rub together can fit the later model main bearings to the early engine block in less than an hour, with no precision machining involved. All it takes is a Dremel tool with a 1/8" wide grinding stone and some careful measurements. No, line boring the block is NOT required. Forget about "rope VS neoprene" oil seals- - - -have the back of the block machined for a SKF #38647 full circle lip seal and forget about rear main bearing oil leaks. That process works on all the stovebolt engines from the 216 to the 261- - - -same seal and machining. There's also a way to modify the engine block and the crankshaft to run main bearings for a small block 400 Chevy V8, but that takes some VERY creative machining that most shops refuse to attempt. RUN- - - - -do not walk away from a hydraulic camshaft- - - -the lifters that are available these days, regardless of brand name, are all made offshore, and they have a horrendous failure rate. Original cams and solid lifters can be reground by any of several shops, and they're 100% reliable.
Changing the bore , stroke, connecting rods, and pistons can turn that 235 into a 270, BTW.
Jerry
