Here's the story. About 12 years ago my son and I got ahold of a 67 and put a OHC6 motor in it. This was when Primatech first came on line with parts for the OHC6. Anyway, 12 years later (a few weeks go) my son is cruising through Texas from Arizona when engine quits in a puff of white smoke coming from under the hood. So, we tow it home, pull the plugs for a compression check and notice that five of the six plugs have melted. Compression check indicates a blown head gasket. So, rather than sink a bunch of money into the 6 cylinder, he's thinking of swapping out for a 400. Looking around, I notice this motor is kinda hard to come by, so I'm wondering about a chevy 350 which is readily available. Also, since we don't have a 400 motor now, we would have to get all the add on's which won't come with the motor, if we can even find one. How available are these parts. Any thoughts and advice would be appreciated......... PS: Why the plugs melted after a 700 mile drive with no problems is still a mystery to us...But then again, we're not mechanics...