If it was me I'd drop in a 727 built to 440HO specs. Those transmissions were rated to over 400hp. Then bolt an aftermarket over drive from
Gear Vendors. For $3000 you get a rebuilt trans with overdrive that basicly will not fail. Even when pushing 400hp off the crank.
No computers to mess with. As a bonus you can set it up to allow you to gear split which is nice to have once you get used to it though most useful on trucks.