I think you're nuts hangin a slushbox off a 235.
While i'm no fan of slushboxes, if I absolutely had to have one, i'd go with the 350 or 400 turbo hydromatic tranny and mate it to a 261 - 6.
I've had enough of those 'metric' 700R4 trannys take a dump on me to be nice and spooked of 'em.
The 350 and 400 TH trannys never let me down.. even after heavy, heavy abuse.