Welcome to the forum. That engine swap is an unknown to most people you will connect with, the engine bay size, the frame rail space for headers, is unknown to me.
That being said, the OEM Explorer 302 headers are terrible, horrendous is a most accurate description. Try hard to avoid those, only use them if you cannot find a better choice. For non Explorers, most other headers made for "P" heads will fit your truck. That's a guess, the 2nd gen(98-01) Explorers have major space issues requiring those odd stock manifolds.
You might do well to search for other swap examples, of similar old Ford trucks. There have been a handful of threads here about old F100's(50's models) etc. Most P headers you find mentioned for those kinds of swaps would be good possibilities for your truck. Also many people have been able to use some normal 302 headers on the P heads. Those 1997 1/2 to 2001 Explorer heads have the plugs coming out at a slightly different angle, so the plug wires are moved closer the manifolds of normal models. So various headers have the pipes located a little closer or farther away from the plugs, thus some may work while most won't.