Right about the floor plate mod and understood on the sm420's 1:1 ratio and the fact that it is still basically a 3 speed with an "optional" super low gear for first.
I've thought about the T5, and the only thing holding me up would be $$ and how to make the differential fit with the new leaf springs I have installed as well as finding the right one (Lugnutz's website has tons of info). I think I would end up needing to buy a differential, driveshaft and having to get the leaf spring perches fiddled with. More than I want to spend now even though the T5 benefits would be great.
The sm420 full syncro aspect would be really nice as well. Honestly, I had thought about finding one of those 100% non-synchro 4 speed crashboxes because I was so fed up with the 3 on the tree hang ups. I seem to remember reading about someone who rigged a wire or string through the firewall and around the 1st gear shift lever so he could yank it into neutral from inside the car rather than pulling over, turning it off, opening the hood, and pulling the lever each time it got stuck! Such a simple trick, I may go make that happen instead...