hi, will a th700 hold up behind a 400-450hp big block? the trans has a fresh rebuild, shift kit, corvette servo and is a non lock up converter. just considering it and looking for input.  

It depends on how it was rebuilt. (ie what parts were used) A 700R4 with right parts can handle about 700 HP and about 700 FT Lbs of torque but it takes more than corvette servo and a shift kit to beef it up. (shift kits actaully increase strain on clutches, sprags, clutch drum splines and such and should NEVER be used on a 700R4 or 4L60e with stock internal parts) You need to upgrade clutches, sprage, clutch drum hub and planetaries and a few other things. Also why you would use a non locked converter escapes me because it will increase average tranny temps on the road. I do not know what you think you are gaining with them converter mod.