[stomper]

Steve,

I am also doing the 700r swap in my '71 SWB. It's a couple inches longer to the mount so not unusual to drill holes for the trans cross member. I am using an ECE cross member and I still had to drill for that one. I would put the 4 bolts in the top too. Others may chime in with having been OK with just the bottom but I'd feel safer with all of them.

Rivets!? UGH I did almost 50 in my frame. Grind off the head, pound it out with a flat punch. ...if necessary.

I read that one piece drive shafts for short trucks and a 700 R should be 56". Measured center of u-joint to center of u-joint. I had one laying around that is 55" or so. I will lengthen it later.

Shifter linkage, just make the geometry work. If you can select all the gears you're good.

You didn't mention the converter lockup switching or TV cable hookup. those are your two biggest challenges and you must do them correctly. There are a few ways to do it depending what trans you have. Search the board and you will find lots of info.