CRANKSHAFT
Any commercially available crankshaft is acceptable. Crankshaft must maintain OEM passenger car production rod and main bearing journal diameters as originally available for the engine type being built. A maximum undersize of 0.035-In. from OEM specifications is allowed on the rod and main journals.Reading between the lines, the 292 journal sizes would be acceptable on the 312 crankshaft. If not, then any 400 scrub engines using aftermarket blocks with the 350 journal sizes should also be disallowed. As soon as I hear from the rules committee regarding the registration form for this year, I'll submit the question regarding the crankshaft journal size.
As stated here a maximum undersize of .035 is allowed on rod and main bearings from OEM specs. The block being either a 292 or 312 (no external difference or casting number difference between 56-59) There would be no reason you could not use an original block with the 292 mains unless yours is a later model block that you have that was never produced as a 312.
I have a couple B9AE's and a couple EDB's that could have been either so it was a production 312, it only had the 292 mains. Whats there to argue, I don't think they have an argument.
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?