Back in 86 when i first built my 250 The skirts on the 307s(mine were popups) had to be trimed to clear I'm guessing the crank (maybe There is a differents in the flat tops or later yr. makeings of the 307 psiton). As for the 327 pistons Thats a 4in bore.hope this helps }[oooooo]



------------------
NovaMan/Twisted6/Larry

Larry/Twisted6
[oooooo] smile
Adding CFM adds boost smile
shocked God doesn't like ugly.