Back to the OP's question: Call Tri Shield - Jim Weise can get you a nice converter for your application.
Hi I have a CK Performance build TH200 4 R, lockup in 4th gear, behind a 425hp/517tq BBB. Has been holding up for 10 years now. Switched to a Hughes street master lockup conv. , 2800 stall with 3.73 out back. So far so good
X2, He built my T-350 for my GS, super nice guy, best part was he's in Akron, 'bout half hour from me.