Gmt800 5-speed to 6-speed swap

So I've got a 2004 Escalade with a NV4500 4wd I swapped in around a year ago and the 3rd gear synchro has gone out. I'm split between selling the car cheap or swapping to a 2wd 6-speed. It works well with the 5 speed but I've never had a need for 4wd (got more capable trucks) and the NV4500 drives like a dump truck. If I keep it I'd go to a Camaro-sourced T56 or tr6060.. I've seen some build threads with Tahoes running camaro transmissions but never much follow up on reliability and I fear the vehicle weight would kill these lighter trannys. It's a swb Escalade with 5" lift, 35s, 6.0, 3.73s. Daily driver, never tow, just a fun rig. I'm not scared to cut it up or do any extra fab work. So, I'm split between swapping to a smoother 6spd transmission or selling it for a different daily driver. Any opinions would be appreciated!