I had the same thing happen to me, it's just air in the hoses sounds like. I would let it warm up and I pinched the hose to push the air. Did this a couple times and kept topping off with coolant and it quit getting hot.
ADM built 417, 2.9L Whipple with 3.250 pulley, ADM ported and polished LSA heads,ADM stage3 cam,ADM LSA belt drive system,ADM CAI race scoop, ADM dual fuel pumps, ID 850's, BMR full suspension, Gforce 9 inch kit with 3.5 inch driveshaft, Street Slayer twin carbon clutch, Lingenfelter oil seperator. Tuned by built by ADM Performance, 740rwhp,685rwtq