Danny, I have one somewhere (?) seems to have gone AWOL.

This has been a topic before and I think you might be able to find it in the archives. Old_Kombi has made one so you might ask him directly.

It's really very simple. If you can fab things, you can make one pretty easily.

It's about 3 to 3 1/2" in diameter with a 2" diameter hole. About 1/2 - 3/4" thick, with tapped holes at the 3/6/9/12 o'clock positions. The 12/6 holes have a countersink on the surface that faces the front of the car. The distance in the same as the bolt spacing on your original MC. The holes at 3/6 shoudl match your new MC. I think an 1800 MC is the only one that is sized correctly and the dimensions are almost identical.

Screw the ring to the firewall with some 5/16-18" countersink-head bolts and install some 5/16-18" automotive studs on the new surface and bolt on your new MC.

Then you'd need a pushrod activator, I used a 6" grade-8 hex fine-thread bolt similar in size to the original rod, but longer. Cut the head off and round the end and voila.