Fiqure out a few engines that you might like and then start searching for a lower mile one from a salvage car-A LIFT OUT---meaning all accessories, wiring harness, ECM and any type of security or theft control module plus fuel tank and pump-if you can get the exhaust system manifolds, head pipes and any sensors ( O2) that are forward of mufflers. You will save enough on just the belt driven accessoies ( water pump, alternator, power steering and a/c ) probably to pay for the whole deal------get trans and don't forget drive shat as just the yoke will save big $$$$$
On the f150 you won't have space issues like in some cars--------
I had a 1995 F350 diesel and the power brake booster was belt driven or ??????? so look for maybe getting brake master and booster-------