Is it possible to run tall valve covers with the stock exhaust manifolds? If not how are you guys using roller rockers?

You might be able to. I could with my old Gil exhaust but can't with my Stainless Marine exh. unless I use two exhaust gaskets. I don't have roller rockers so I bought short valve covers

I had the tall valve covers on a 454 and bought revolution marine exhaust had to use 2 sets of gaskets and had about 1/32 of gap between the valve cover and the exhaust. I know its not a 350 but maby you can use this info somehow