if gets hot at high speed, could be:
engine coolant needs flushing
lower rad hose is collapsing
radiator not completely full (have a recovery bottle, not
an overflow bottle)
engine compartment too tight, which limits air through radiator
Aluminum radiators are the way to go.
I have a front splitter which makes more air flow into radiator
Have a separate tranny cooler, and bypass the radiator.
Use Purple Ice coolant treatment from Royal Purple
Make sure total timing does not exceed 36 BTDC
Use higher octane gas
Make sure have a fan shroud
72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.
1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"