The 4L80 does have some weakness in the overdrive drum/sprag section, heat is the enemy of automatics, I would plumb in the cooler if at all possible.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy