[updated:LAST EDITED ON Oct-04-02 AT 07:17 PM (CST)]If memory serves me right, it will not fit the 350. It will fit the 327-283. A believe a later model bellhousing from a 70's truck (307 or 350 ci) will work fine. So long as the bell housing you use has the same mounts as the one that's there now, the driveline should be fine.
Some folks move the motor mounts forward one bolt hole (about two inches forward) to allow an HEI distributer more clearance off the firewall. I'm not real positive on if that can be done to a standard shift trans as I've only seen this done on automatics.
I have a later model 307 with HEI hooked to a granny 4 speed and it all bolted right in on the factory V8 mounts. The HEI is close, but does not contact the firewall. I took the opportunity at the same time to install a one-piece driveshaft too.
DV