Ditto here on my son's 347 with Trick flow heads and intake. Had to cut out that protrusion in the 1250 gasket into the water jacket. It will be fine once modified.

.....John

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1969 Fastback-1 owner-302 TFS Heads, Bigs 650 DP, Comp Xe262, Speedpro Rollers, Vintage S2MS Cobra intake, Flowtech Ceramic Headers, C4- JPT valve body, 2600 stall, 3:55 Detroit.
1969 Mach 1, 428CJ, 4 spd, 3:50 trak loc; unrestored