The Ford adaptor is relatively scarce. Avant Salvage in Georgia had approx 35 Frito Lay trucks with Cummins 4B's in them, and only one had the Ford pattern. The adaptor had already been bought by someone, and Benny, the yard owner said that they dont last long when one shows up.
What you can easily do though is buy a steel bellhousing from Lakewood, the racing folks, and weld and/or redrill the transmission pattern to fit whatever transmission you want to use. Easy to do on a steel bellhousing, not so easy to do with a factory housing as they are either cast aluminum or cast iron, neither of which lends itself to rework like you would need to do.