On early Bay window buses (68-71), you need a block with the three mounting points to bolt on the support bar at the rear.  If the block doesn't have one, you can get an adaptor that bolts on over the oil pump . . . but I'm a big fan of them.  I don't have any personal experiance with one, but the mount just doesn't look strong enough to support the engine for a long period of time.  Other than the mounting points, you shouldn't have a problem.

They are a bit cheesy..... i had one on my old bay, always leaked a bit of oil too. 

Those adapters will do a "number" on the oil pump mounting studs sometimes along with the oil leaks. Did the rod tear up the block or did it just burn up a bearing.