MSD ignition installed, now I'm thinking transmission time?

An HEI upgrade with the other things he did is about 100 or less. Just FYI.
833OD manual trans is a good upgrade. The A500 will need a custom bell housing and some body work. Contact (Lou Dart 270) over at slantsix.org as he has done this swap. The only autos that can bolt right up to a slant 6 are the 904 and 727 and ONLY those that were built for it.
Frank