which oil should i be running?

On a roller cam, anything works. Even canola. As long as it wasn't used to fry cod. Don't reuse for french fries like DQ does. Smells funny.

10w30 if it's a recent rebuild. 10w40 if it sees towing, high heat, low speeds, higher milage. Synthetic oil does a better job at keeping viscosity consistant between cold and warm temps. It also finds leaks easier, but if the engine has a nice seal, you shouldn't worry. You don't have to worry about zinc like folks running flat tappet.