There's an excellent tech article in the new nov. 03 5.0 Mustangs and Super Fords. They took a 5.4 out of a 00 e-150 van. Quoting article ... "How much did the swap cost, you ask? The 5.4 found at the recycler for $1,150, and the stock motor brought in 450. All told, with miscallaneous gaskets and billet aluminum for the adapters, it was less than $900 to go from a 98,000 mile stock 4.6 to a 4,000 mile 5.4 with a lot mroe potential."
Obviously this doesn't say anything about installation charges, but they would not be bad at all because the only thing changed on the e-150 engine was using the stock gt intake. All other components from the heads, the cams, and the internals are exactly the same!
They picked up 30hp and 90lb/ft of torque to the rear wheels. This is a relatively cheap swap and the gains are tremendous. More of the older mod motors should be looking towards this swap I believe. Only problem was clearance for the intake which was easily taken care of with a handsaw to the hood.
This is a SOHC setup, but is still worth it IMO.