The correct term for what I think you are asking for is "adapter"...and, yes, they are available. Tom Langdon's Stovebolt Engine Company (maybe slightly different name), Wilcap in California, Bendtsens in MN (www.transmissionadapters.com), Buffalo Enterprises...........are a few that come to mind........do a Google search for those for which I didn't provide a web address. Ray
I wonder if anyone has tried to do the following: Take a 216/235 Powerglide adapter (mounted to the 216/235) and put studs in the Powerglide threaded holes. Then take a V8 cast iron Powerglide adapter plate and drill out the Powerglide mounting bolt holes. Then place the V8 adapter plate backwards onto the 216 adapter plate and fasten with lockwashers and nuts. Then mount the 350 to the V8 adapter plate using bolts, washers, and nuts. Sure you will need a crankshaft spacer, but what the heck, it might be cheaper than buying a kit from at least Bendtsens or Wilcap. Stovebolt and Buffalo are reasonable I believe. Just a wild thought!!!