V6 to LS 5.3 in 97 C-1500 W/T
 

What do I need to get for motor support towers, and bracket for A/C compressor, oil dip stick and tube, and starter.
Are there any adapters or changes to use same transmission?

I went with an 6.2l LS3 but should be similar. For the mounts you'll need to remove the stock brackets that the motor mounts are bolted to and move the mounts right to the frame crossmember. You can check out my build thread, should be pics of the old V6 mounts and the new V8 mounts. I used the Holly brackets for the A/C and have the stock truck compressor, along with the alternator (had to go with an earlier Camaro alternator to get it to fit around the steering rack). Dipstick and starter are stock LS, work just fine.

Can't help with the transmission, I went with a TR6060 in my truck that came from the same Camaro SS as the motor.

Rock