Turbo Converter for Ford 4r70W


It's my Granny's car!
I just bought my old 91GT back. It has a 70mm single turbo and T5. I'm going auto with a 4R70W. Might be a manual vb or the Microsquirt trans controller. But I need an idea on what converter? The shortblock has stock crank, girdle/main studs, shot peened rods/ARP bolts, SRP forged pistons/coated skirts, Lightly ported stock heads with stock valves/3 angle v job, and a 88 speed density stock cam.
I will be limited to 450-500hp due to stock block and shift points will be 5200/5500max.
It has Megasquirt Gen2 Pulg and Play and I have the tune pretty much dialed in. Dying to swap the auto in and launch off the 2 step!
10", 9.5"? Will need to be lockup for road trips.