Once the motor "normalizes" there is no difference in operation. Your cam is not causing too much heat by itself, it's the additional horsepower which increases the heat that must be removed by the beefed-up cooling system (and the clogged water passages in the 35yr old heads and block). 
My tri-power 455 used to warm enuf in 3-4 blocks to idle on it's own, now it takes 5-6 blocks to idle without raising the idle against the brake when stopped. I gutted the choke and stroke the pumps twice to fire it up.
Try it, you will like it. 
Les
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Les Iden
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'65 Buick Sport Wagon Custom, 340, T350, 3:23
'66 GTO Post/468, 700R4, 3.31 (Mike's as of 9-16)
'68 Grand Prix/455, dual AFBs, T400, 2:93 posi (sold)
'72 TA tribute/461, T400, 3.08, (Russ's as of 9-16)
'97 Mitsubishi Eclipse Spyder Turbo, Konis, 5 speed
'09 Torrent GXP, nav, Sun & Sound pkg., Bilsteins
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