Unless you're putting that BBC in a Dusenberg, notching the firewall with a pre made, rivet in assembly would be a hellova lot cheaper . . . and simpler.
About the only reason one would really need a front distributor would be because you're making spare parts at above 8000 RPM with a Magneto. A mag pulls so hard on the back end of a camshaft at high RPM that it progressively retards the valve timing and Ignition timing. A Mag will pull so hard it will actually twist the cam . .
We discovered that back in the mid-late 60's in a Jr. Fueler with a 310 inch SBC. But back then there was no fix. At least for the Chevy's. But the guys with the 354's and the 392's jumped on it and If I remember correctly, Dave Zeuschel built the first front drive timing cover for the 392 . . That by itself kept a lot of those 6-71's in one piece and on the engines . . .