cast iron water pump vs aluminum pump

plugs are grey/tan when pulled after cruise shut down, and they are tan/to light black after extended idle check. I found a post about a radiator support seal that mounts to the hood, mine was missing. made a rig with some 1" id water pipe foam and drove it again tonight.now it seeems to hold temp just under 220 at cruise, but still wants to climb in traffic. Could the stock exhaust manifolds be holding back to much exhaust and maybe causing or adding to my heat issue? I have a set of tti headers on order so I will find out soon enough they help or not.