I have done this as have a couple others. You need a different bell housing to match your SM420 Trans, (I think we are talking about the same trans). I bought one from Jim Carter, but I think a good machine shop could do the modifications if they saw what was required for a pace to bolt on the pedals.
I was told by someone that possibly a 47 or 48 bell housing will bolt to your new trans and have the bolt hole for the pedals. I have never seen one of these but it may be true. Maybe somebody else can help on this one, I am not sure.
I have a 1 ton and was able to get it in without moving anything on the frame for clearance. I had no problems with the master cylinder.
The SM 420 is much bigger than old trans, so you will need to cut out some of the floor board for clearance, and probably have the drive shaft shortened.
