I agree also,you can change anything on a Bronco to make it what you want,but the paperwork part can stop it in it's tracks.I would say it depends on the smog laws of your state. Look for the latest model that is smog (or smog test like in CA) exempt. As much as I hate body work, I hate dealing with smog requirements even more.
Example:
There's a guy here who swapped in a Mustang EFI 5.0 in his Bronco. The year of the Mustang he got the engine from had 3 catalytic converters in it. What did he have to do? He had to put 3 cats under his Bronco. I think it's the cleanest running Bronco ever, not counting the propane guys.
Years back when I lived in SoCal I had a 66 VW and at that time the state had a rolling 25 year old smog exempt law.The year before it was to go exempt they froze the law at 65 and back...That did a lot for the value of 65 Mustangs because the 66's had smog pumps and needed bi-annual inspections.
Oh by the way I sold the 66 VW and bought a 63. So when I went looking for a Bronco the 2 priorites were smog exempt and RUST... Good Luck