Is the '99 4L60E any good?
Heads/cam? Always use a cooler and by all means compliment that heads/cam set up with a nice TQ-converter.
Do not manualy shift the tranny... do not "get on it" in OD and change the fluid often. You should be fine....for a while.
If you do have it rebuilt in the future, go with a vacuum pressure modulator.
99's didn't have much, to any issues with torque management, so your fine there.



