Took my 67 big block to my machinist a few weeks ago and had it tanked and maged. Turns out the block is craked and can't be fixed,so I take his word for it and tell him to find me another block. So a couple days later he calls me up,say's he found a 66 block for 300.00 dollars.I told him o.k. go ahead and do the machine work and I'd bring my cam down to have it groved on the rear journal.So he does all that and last friday I pick it upand take it home.Then last night I decided to check the block # it was 3935440 witch acording to two of my rebuild books says its a 68 block witch shouldn't need a grooved rear journnal.So now i have a block with a grooved rear cam bearing with 3 holes in it, a cam with a grooved rear journal. What's the best course of action hear? I don't think I should go ahead with this set up because I think there might be oiling problems. By the way I checked the block for casting dates but couldnt find anything ledgable.

Carl,
Having the grooved cam will not hurt anything. However, make sure that the rear cam bearing is going to work. I will try to look at one at the shop today. I am pretty sure I have a set of the old style cam bearings to look at. I might not be able to get back to you until this evening.

The old style bearing will have 3 large oil feed holes in them,approx 1/4" dia.1 to feed the journal and the other 2 feed the lifter galleys.

Took the block back to the machinist and he took the rear cam bearing out and did find a groove in the block under it so it was a 68 block.So he fessed up to his mistake and put the correct bearing in and is going to buy me a new cam and credit me the money that it cost to groove the other one.Thanks guys!