I just checked and it appears Special Interest Arms has gone out of business... Too bad, I have one of his conversions and it works good. I don't know of anyone else who makes them, good luck with your search!
DW
@deltawiskey Yeah I talked to Richard a few times before he closed up shop. He was supposed to email me back with an adapter he said he had a few up laying around but never did. Currently working on an adapter to use G36 mags but the old school original looks with a 1911 mag would be neat to have
Troup Systems used to do a kit as well but shifted to Mauser kits lately. They says it is a possibility they would run some more in the future but haven’t been very responsive in emails to try and acquire one either.