The Explorer 302 is essentially a Cobra 302 without the Cobra cam or roller rockers. The rest is virtually identical to a 302 Cobra. the intake and heads make the same power as Cobra parts, because they are all GT40 parts.
All 302 roller engines require the hardened steel distributor gear, and all use the same pushrods, have the same compression, firing order, and use a 50oz balancer.
There were only three Ford 302 roller cams, the HO cam, the Cobra cam, and the truck cam. Obviously the Explorer has the truck cam, which is the same cam as the Lightning 351 cam, same part.
You don't need to replace the lifters if the engine is in good condition. BTW, the Explorer oil filter block adapter is a metric part. If you want to screw an FL1A onto the block, you have to swap that block adapter, which takes an Allen tool, large, about 7/16" or so.
Select the cam based on what that 90 Mustang needs, the HO cam is great for most anything until you modify the head/intake/exhaust flow quite a bit.