Transmissions with lock up converter's have been around for 30+ years (TH-350C, TH-200C) and I've never seen a disclaimer for a shift kit that said "DO NOT use on lock up converter transmissions"  A lock up overdrive will reduce fluid temps while cruising simply because slip is eliminated.  In any case rather a higher stall converter or shift kit is added to a car it is assumed that the trans is going to see duty more severe than stock and an aftermarket trans cooler is recommended.  In general the shift kit will increase the life of the trans, it's the mis-adjustment of the TV cable that kills it. (Unless you use TCI's new 700R4 line pressure valve)