I've been folllowing a thead over on the Project Zero G's Forum I thought was quite interesting. Bill Hincher of Japanese Auto in Toledo has cast a run of bellhousings to bolt a Toyota W and G series transmission to a Mitsubishi 4G63. He'd had some requests to modify his bells to bolt up Toyota R154's. The thread covers his work. He also came up with a spacer to take up the distance from a long shaft Toyota transmission to a short shaft one. Might have some applications over here. Take a look.
http://projectzerog.com/forum/viewtopic.php?t=382&postdays=0&postorder=asc&start=0Greg