Originally Posted by treerootCO
The head casting numbers on a 2f are:
61030 or 61031, open chamber (domed pistons)
61040 or 61070 closed chamber (flat pistons)
And I believe the f.5 head is 60051 and also possibly 60050 (closed chamber) This would be flat top piston compatible on 2f that came originally with domed pistons from what I have been reading.