Forged 273 crank in an early 360 Block?

Anything is possible, but sometimes you have to ask yourself why (especially if nobody else has done this before). First off ALL A series engines had the same width main bearing, the DIAMETER changed for the 360. This was to maintain crankshaft rigidity through journal overlap. A stock 360 or later 340 cast crank was not exactly a weak piece.

Welding up such a crank on all 5 main journals and then surfacing would cost quite a bit if you paid your friendly neighborhood machine shop to do it. Probably near the cost of a rebuildable 340. Plus, if you are starting out with a 360, why spend bucketloads of cash to reduce displacement?