I believe you can replace the MOA with a Timney or Jard, but I don't believe there is an option that allows you to install the "old" trigger.
If you google ernie the gunsmith, he offers a replacement spring that makes the trigger better, but, IMO it doesn't feel like the "old" trigger. Personally, I've given up on the new 70's and their MOA trigger. I own to many 70's with the old trigger and it doesn't feel the same to me. It sucks. IMO, the new actions are much smoother and probably better built, but I can't get past the trigger. I tried, but it was a no-go for me. YMMV.