Thanks for everyone's input on this. Very helpful. ?I still plan to stay with the 258. ?I don't want to throw any complications into my son's first rebuild. ?Since the Spirit currently has a serpentine belt, I'll try to find another that also has a serpentine. ?This should make it easier to reuse the accessories. ?It shouldn't be too hard to find a stray 258 out of Jeep. ? I already have a rebuilt 4.0 head from Clearwater Cylinder Heads. ?It comes with the necessary holes welded, ready to install. ?Now just to find the time and the money. Todd