How do you prime a new engine?

You buy a priming tool. For a small block Mopar it is a hex shaft which fits into the oil pump with the distributor and intermediate shaft removed. For obvious reasons, you want to prime before you glue the intake down. If you made sure nothing went together dry when you assembled the engine you should be fine. The factory makes engines all day long and doesn't prime any of them.

Torco sells their MPZ Assembly Lube in a spray can. This stuff is wonderfull; its sticky, it clings and is more slippery than buttered whale snot. This stuff sticks to metal so well, it takes 0000 steel wool soaked in lacquer thinner to remove it. Basically this is spray cam lube (as an aside, I have installed more than a couple cams using moly-EP wheel bearing grease with no problems). Buy some, it will become one of your most reached for cans of spray goo.

Long story short, as long as you oiled/greased everything as you assembled the engine, you should be fine.