Spray-on oven cleaner and a pressure washer should work just fine.

 

I used brake fluid to clean the goop inside... It doesn't evaporate as quickly ether and acetone based products, so it stays around a lot longer dissolving the old oil.

I should of just purchased a mopar or edelbrock

 

m1's have been discontinued so theyre going to be pricey-er, and even more rare now.

 

Should I use RTV on the gasket ?

 

This. Let the oven cleaner sit for a while, spray with clean water, and repeat as needed.

 

Will that work on the inside/outside of 30+ year old valve covers?

 

Over cleaner is good for iron, steel.. I use it often.. Stainless, aluminum not so good..

 

It will work just fine but it will etch it, I was not going for looks I was going for cleaning.

 

So it will work for old valve covers?

 

I missed your post, yes but always to a small test area first. It's a old Hot Rodders trick, Google search has info about how to do it and what metals it works on.