I did that on my 66. It's pretty straight forward but it the little things typical with anything that pop up. Such as the speedometer hole in the firewall is a different location, LH pitch speedometer driven gear and a few others. I took a bunch of pictures so one day I could make a post for this.
I'm using sealed roller bearings on my peddle hanger, made my own clutch linkage with rod ends. Works great. I thought about a T5 and even went so far to buy one. It's sitting in my basement. I like the 4 speed very much. I still have my 2.8's The 2.78 1st gear is low enough to start off pretty easy and cruises nice at 70. Not too high, not too low. The Toploader is much, much stronger too. PM me if you have any questions.
My linkage, very easy and cheap to make.
Knock out location in firewall for clutch rod. Like a knock out on an electrical box, it's there just knock it out
peddle hanger bearing, I highly recommend!