Apart from casting numbers look for, screw in rocker studs, a cast built up area around the valve spring seats, twin point Ford/Autolite Distributor, a thin counterweight on the rear face of the crankshaft timing gear in front of #1 main cap , 3/8" con-rod bolt's(9/16" hex), pushrod guide slots instead of round holes in heads, fully machined f/r faces of #1 thru #4 main brg caps, and a front damper with a full outer ring ( counterweight in hub ) approx 1.5+" wide and only three bolts for mounting pulley. Cast exh manifolds if still with the motor will look like a Semi-Header. Camshaft was solid lifter so lash clearance of approx 0.020" should be present.
Get ALL of these features and any genuine p/n# that Im sure other members will give you and you will be one lucky punter.
Jac Mac