I was in same boat at 102k ... 4.6l with hole in piston. I had another 4.6 and went 225k and still going with no major repairs. Long story but I wanted it fixed right. Had a dealer install ford reman, all new rubber, new injectors, it came with a new water pump too. Then a few thousand miles under warranty a cam hold down cracked. Different dealer replaced entire cylinder head. 55k miles later it is a daily driver. Also after the engine was changed, I cleaned throttle body out, new coils, entire walker exhaust with new cats (the old ones were oiled) and 4 new oxygen sensors. Then front wheel bearings, all new struts- quicklift, and 4 new alum wheels, fan blend door, and turn signal stick.
The repair shops do not want to tie one bay for 14 hour of book time, risk of nonpayment. And keep in mind it is all negotiable. Look at Tasca parts etc and use a level. 2nd opinion is good too... probably need a tow. If you like the truck go for it. New ones are way too expensive!! Used do not really know what you got either.