The original oil filter on your Willys would be the canister style. In fact "back in the day" the oil filter was an option that was usually installed at the dealer if the original purchaser paid the extra cash. Most of the cars came off the assembly line with no filter.
The thing to remember though is detergent oil was a rare item back then. Today, nondetergent oil is hard to find. With no filter you should only use nondetergent oil because that lets the carbon, metal particles and other crud sink to the bottom of the oil pan out of harms way. Detergent oil keeps the junky stuff in suspension where it should be cleaned out in the oil filter. With no filter and detergent oil, the nasty stuff runs through the bearings and such and can cause premature wear. It's nothing to worry about if you're going to use your Willys for cruises and Sunday drives and do frequent oil changes. But, if you're going to use it as a daily driver or take long trips with it, either run nondetergent oil or install a filter.
Luck,
Old Willy