of thumb.. You can always use an exterior product on interior, never use an interior product on exterior. Exterior products are doped with a much higher level of UV inhibitors.
Personally I like the Interlux
Gold (Ford, Chevy?) as it handles closer to a traditional varnish than Epithane but that's just me. Thin Coats, a tack rag in between, and reasonable care should give you a result you will be happy with with either product.