Transmission swap

Neutral safety is a non--issue. You should already have the proper starter relay, which has two "push on" connectors, just connect the one that went to the clutch safety switch down to the center post of the NSS

904/ 727, simple. Just deal with the driveshaft.

Be sure you research the balance issues (I'm not sure) with the magnum versus LA engines for converter weights or flex plate.

I run a 727 with an "all manual" valve body. Mine is reversed pattern, but you can buy them either way, and I just love it. I'm in the same boat as you---arthritis, I cannot "row" a gearbox anymore.