i recently got a 1976 440. the guy said its either from an RV or a 3/4 ton van he cant remember. he was a cool guy, knew his stuff, he had a nicely restored A-body with a full cage and a 360 in it.
anyways i am going to buy a full rebuild kit for this engine and i dont know which bearings to get.
i mic'd the journals and they are 2.375 just as they are stock and i plastigaged the crank with the old bearings and it came up with .0015" clearance? is this an exceptable clearance? the bearings have 001 US stamped on them, are these standard size?

on a side note, the heads have green valve springs on the exhaust valves, the guy i bought the motor from said they are higher tension, is this correct?

 

.001 is ONE thousandth undersize. They may have been factory If that is what they are, you don't want to put "standard" bearings in there. Do NOT confuse .001 with .01, (10 thousandth) which would be a ground undersize journal.

Look in your shop manual for "special markings." Some engines came from the factory with one or more crank journal undersize from the factory.

From the 72 shop manual:

 

thanks for the info! i dont see any of those markings on my block pad but my crank does have R 1 -2-3-4-5-6-7-8 M 1-2-3-4-5 on the third counterweight

 

I don't guess. I take it to a trusted crank grinder. Your crank journals could be out of round and you will not be able to check that with mic or plasti guage. Mine charges 60 bucks to turn it .010 on the mains and rods. He chamfers the oil holes and polishes it. That takes all the guess work out.