Not to get off subject but I believe Crites has the parts needed to swap a FE into a fox body and Canton makes the oil pan for that combo also. I think Shawn LeBlanc is campaigning a FE powered fox body Mustang, and Rory McNeil is running a 428 powered Fairmont up in Canada.

If it's the original engine for the truck it should be a D4TE casting (possibly a 501/105 mirror) which can be either a 360 or a 390. Same bore, just a different reciprocating assembly. Some of these blocks can handle the .080 overbore to turn it into a 428 with the right crank but the only way to know is having a sonic test done on the cylinders.

If your block can't take the .080 overbore, Scat imports a cast stroker crank that turns the 360 and 390 into a 422.

The heads D2-AA or D4-AA should have the bosses on the exhaust side so they can be drilled and tapped for the 14 bolt exhaust manifolds if this engine winds up in an intermediate body (Torino/Fairlane) or a Mustang.