Does your state have yearly inspection? If so you will need a motor the is from the same year of your truck or newer and also made buy the same company. So that narrows it down to either a 4.6 or a 5.4 and that means big $$$$$.
I have state inspection, well, county inspection. They just look to see if you have a cat. converter and they plug it up to check for codes (on 96 and newer) or sniff the exhaust (on 75-95). The only other thing they test is the gas cap, they don't even open the hood. So it just depends on how the inspection is done. Also, unless they pull the starter off and pull the nyumbers on the block, how are they really going to know what year the engine is?
Well, I was offered an engine out of a Mustang GT with 55k miles, plus it came with some pulleys, cold air, bbk headers, T-5 tranny, and all electronics for $750. Full crate motor plus tranny, for less than a grand. There are small expenses still, like radiator, fans, gauges, water and oil pumps, possible steering modifications.
If that helps with expenses.
Then for times, according to the TRS tech article, it will take 50-70 hours of work.
I did have other engine offers. I could get a long block HO engine + an AOD for $200, or a 351 + C6 for $300. Then I would still need an intake and all.
I personally wouldn't go through all the trouble of wiring the Mustang stuff. Id sell that and the T5 ( a POS anyway) and buy an exploder 4r70w and the explorer wiring harness (I do mean everything too). Or you could get a 96-03 Ranger harness for the "firewall back", and use the exploder engine/transmission harness and PCM. It will be as good as factory when you are done though.
I bought a junky old '93 Mustang LX 5.0 5spd for $1,200 a few years ago to use as a donor for a beautiful '93 GT roller that I had bought. Mechanically the car was in great shape before I dismantled it. I would say that a full donor car might be your best bet if all you are really wanting is a V8 on a budget. Keep your eyes open and be patient.
Why go through it for a friggin Mustang engine though? Take an Explorer 302, add the Cobra 1.72 roller rockers, and you have a COBRA engine .
Add somke torque monster headers and get a tuner and there you go, one bad *** truck.