I have a LQ4 mated to a 5 speed manual (NV4500) in my 2001 Chevy 2500. The truck weighs 6200 lbs and is used offroad. 35 inch tires.

My LQ4 has:
Wait4me tune
Electric Fans
Ported throttle body
airaid modular intake tube w/ K&N drop in
Pacesetter LT headers
3 inch true duals (NOT mandrel bent) with factory cats, and Dynomax x-flo muffler

I have the 317 heads that I will have milled 0.040 which I think would be around a 10.5 to 1 compression.

I am thinking about this cam:
Comp Cams LS1 XR269HR-14

I am open to other cams though.

Do I need any supporting mods? Will I need to replace springs, pushrods, timing chain or anything?

 

get some valve springs for sure...push rods are recommended but optional as well as the timing chain