Recommend products to use if you have done this in the past !!!

I assume those are iron heads. If so, water on bare iron will cause
rust in a short amount of time. I prefer to take a rotary air tool
wire brush to the gasket surfaces and any other surfaces I want clean
(anything that will be painted). Once all the crud is off, I hit it
with a blast of carb cleaner (I use Gumout spray) then blow dry.
After it's dry, it should be ready for a coat of primer. There are 3M
gasket removal pads but those can be aggresive enough to remove iron
if you're not careful.