ya thats it

copper exhaust sealant, it's meant for the manifolds. I know napa sells it I used it once... Or you can buy a gasket... but not worth your while I THink.

i'll do the gasket, its the "proper" way to do it
i may clean up the headers and wrap them or something

Definitely the best way.Those putty's are temp fixes and i've seen them leak many times later down the road.If you were selling the truck and just wanted to get rid of it,that would be fine.But since you're keeping it why not do it the right way.

Heat wrapping the headers is a good idea as well.