Keep the Duratec. That engine is CAKE to work on and deal with. PLus being in the PacNW, no rot to deal with. Cheap parts too.
The only seals you can still get from FoMoCo for a V8SHO:
Valve Cover gaskets, spark plug well gaskets. That's it. And supply is dwindling fast, as the gasket manf. date on the bags is 2010-2011.
Rear main seal, front crank seal, head gaskets, camshaft seals, timing cover gaskets, etc. All gone. Intake gaskets you can lightly coat in black paint, wait til tacky, then install.
Coil on plug assemblies are about same price as a 2000, 2004-5 DOHC
coil on plug. Keep in mind general parts availability. IAC
is shared between SLO and SHO
or other FoMoCo products. Otherwise, things like the Thermostat (V8SHO only), AC
compressor (V8SHO only), alternator (V8SHO only), PS Pump (V8SHO only), Water pump (V8SHO only), etc. They barely made 30K of the V8SHO, so parts availability is small, and expensive.