I recently pulled a 248 from a 55gmc1001st. The original owner was general automotive machinists in Chicago. They had rebuilt the motor in 1972 and had the records. Fortunetely they are still in operation. Third generation shop; son and grandson are still up and running. They had a cam and a crank .010 from previous jobs, full knowledge, equipment, talent and honesty.
I had alot of valve adjustment issues prior, the valve seat depth was off and that along with head milling made the pushrods hit the bosses of the rocker arms instead of on the adjustment screw balls. *WHEN HE SEATED THE HEAD HE USED A STRAIGHTEDGE TO ALIGN THE HEAD WITH THE BLOCK AS THERE ARE NO LUGS FOR THE BLOCK HEAD.* These people have knowledge from the thirties, they pay close attention to details and they have total integrity.

The owner is named Greg, they get honorable mention.

Paull