I think that might make a good muffler for that engine...and it just might help the performance like the .46 size muffler helps with those engines?

I just so happen to have a couple of older Webra Speed .61's that need mufflers (hint, hint) so...if you do decide to make an adapter...perhaps you could make and "extra" one for a reasonable fee ? (PM me, if that's a possability)