Where to buy GT-40P Heads

In case anyone is curious this is my plan for the 168K stock motor. It has good compression, doesn't leak oil, and with the valve covers off there is no sludge on the heads. I'm adding new heads, intake, roller rockers, gaskets, etc. Also the Prochamber is coming off and the emissions equipment is going back on with a Magnaflow x pipe and Ford Racing Ceramic "P" headers. Something to up the performance while I build a better motor. I'd do the engine right the first time but I need brakes, tires, and I'm tossing the AOD. Cobra brakes, new wheels and tires, and a TKO 600 or T56 depending on how much I feel like spending. :shrug: