Need lots of trans help

I smoked the trans yesterday. It would lock up and stop the truck in 1st, and barely move in 2nd. I have had some issues before with the last trans, ending in the case being cracked. I want to build a better mousetrap here and need to know what the good parts are. I am strongly considering getting one of Frank Merkl's valve bodies with a trans brake and manual valve body, so that part is handled. Second phase is to get rid of the heavy cast iron 205 T/C and replace it with a NP208 or BW1356. I have the BW unit, but the 208's are easy to come by also. This last trans was a lucky find that a buddy had laying in the corner. It was covered in oil and dirty as heck, but after taking the power washer to it, I found a rebuild tag on it and it was a very fresh reman. It did well for two seasons before locking up on me, but that is still pretty bad longevity. I have the one with the split case and it has the red clutches in it, and a kevlar band. I can strip out those parts pretty easy, or just get some new stuff. Clutches and a band are maybe $100. I know there are several other upgrades that can be done, but I need to know what they are. The servo is one area IIRC that there are quite a few options, and then rollerizing it too. I have been running CIH Hytran for the fuid, and it seems to hold up well, untill I start making a lot of back to back passes. I have a huge trans cooler on it now, but I think I'm going to go old school demo derby style with a coil of copper in a cooler filled with ice to help. Any help appreciated.