oil coming through cylinder head exhaust

if its coming out of the exhaust port itself its a headgasket. if its coming from the outside its probably as stated the valve cover gasket.

I'd take a look at the valve seals.

Oil in the cylinder could come from a head gasket I guess but that's doubtful. More than likely the valve guide seals are worn out.

Also starting a car once a week is worse than just letting it sit. You need to take it out and drive it to get the oil up to full temp and flash off any water in the oil.

I would do a leak down/compression test before going any further. If you're ok with that then move forward. If not then you need to figure out the cause before you change the heads.

FelPro Performance makes good gaskets. Ford Racings M-6051-A302 is a FelPro gasket in a Ford Racing box. It's a bit cheaper, will work great in your application, and at 30 bucks a pair a very good deal.