Knock and smoke

Put pressure into the radiator with a full fill and see where it starts to seep. Stethescope helps alot. Pull plugs and check cylinders, pull covers and check lifter valley. Its either intake or head gasket and cylinders will fill if its a head gasket. No break in needed on a used cam and lifters if they are put back in order, reused same cam and lifters in 3 Ford 351C motors once, back in the LEAN high school years...sweet motors in light cars.