The original would have been a 228 or 248. Chebby engines then would have been the 216.5 or the low-pressure (POS) 235. Stay GMC - the engines are far better constructed than the Chebby powerplants.

Unless the Chebby motor has been switched, it's a low-pressure babbit-bearing motor, and I'd avoid it like the plague.

Get a REAL truck, get a GMC! www.oldgmctrucks.com
1954 GMC De Luxe COE