I thought I just read recently where the 256 merc manifolds were EBV's and the ford 239's were the EBY's, so that may rule out coming from a 54 Merc and may be an early Ford manifold. Unless I got this backwards. What color was the manifold? that may give some clues.
I have a strange manifold with a 2 Barrel Teapot holley and the smallest 4 bolt carb pattern I have ever seen. I don't know if there was ever another carb made to fit this manifold. Maybe its off an industrial application? I'll gets some pics.
55 Vicky & customline
58 Rack Dump, 55 F350 yard truck, 57 F100
59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?