Jim, hunt around on this site for a while before you start to finalize engine plans. There is a lot to learn about so many combinations and possibilities.
Most first engine ideas or impressions will revolve around an engine from somewhere else, not an Explorer 96-01 model. All of those are or will be hampered by their operating system, carburetor, or front engine dress.
The real OEM Explorer 302 and its complete system of parts is far far superior to any other non Explorer engine system. I/we have pointed these points out to many many people, it just takes a lot of time for people to learn or believe these things.
All of the other combinations cost too much in total because they include parts that are not needed or desirable. The "Boss 302" for example will have the wrong oil pan, pump, cam, timing cover, valve covers, intake, carb, and flywheel for starters. Those are expensive parts.
It's better if you read about what combination choices are available, pick a power level, and then decide how to build the engine. You can build cheap just over stock for $1500 or so, or $7500+ for a high end engine plus supercharging.
Most people select something in the middle, stock block to bare $2500 block, stock piston/rods up to $1000 piston/rods etc. The key is deciding what compression, boost, and driveability you want. That will steer you to a price range.
My example; I'm planning to swap in a stock 74k Explorer 302 with added cam, timing chain, and out of box aftermarket heads. I'm going to choose the heads for use on a stockish 302, to be able to resell them soon. I also need to use heads with the same exhaust bolt pattern as my final heads, to fabricate headers for. I shall not ever pay $600 for 1.5" primary headers for a V8. I remember when $75 was the going rate for good headers, not small headers, good headers.
I just need a capable engine to mock up and first test a custom supercharger. I do not want to push boost to a $3500 engine and blow it up. I don't mind risking a used stock engine. I'll get that engine running right, then build a good engine to swap in.
Use the "search" feature to hunt some of the other engine build threads for OBDII PCM's. Regards,