Some early windsor blocks do not have steam holes drilled above the cylinder bores. I found this out in the insallation notes for trick flow heads. Trick Flow says to drill these holes for twisted wedge heads. I don't know if that is your problem, but it migh be worth looking into.
http://www.trickflow.com/product/twi...twiswedge.htm#
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67 Fastback - Arctic White Pearl paint
351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Comp. Cam, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.
My 351W Fastback
