Some info and such for the OP, and anyone else who finds one of these under their hood...
That link indicates that with the factory intake manifold, this engine can accept a standard-length big-block HEI dizzy. Ok, so who's right here, PG59 or the author of this link? LOL. Possible upgrade for the OP. One other thought -- Something occurred to me from another post...
If anyone remembers my post about engine paint color indicating a DT466E vs a MaxxForce DT, I believe that may be the case with the tall-deck big-block Chevrolets as well. Most 366s I've seen pics of were painted blue, the pics of 427s were either red or Chevrolet orange. Hope that helps someone in identifying these in the future.
An interesting thought I'd like to intone here... The 8.2 and 6.2 Detroit Diesel engines wound up in highway applications simply by a farce of sorts. The 8.2, from my understanding, was originally designed for marine applications. Legend has it that the 6.2 was originally designed for the military for generators, pumps and such.
Story goes that such an engine was orphaned when the equipment it powered was no longer serviceable apart from the engine. Military mechanics stuck the orphaned 6.2 into a military truck that no longer ran and apparently the military asked GM to build CUCVs with the 6.2, and it eventually was offered in light-duty civilian truck offerings as well.
What makes this relevant to this post is that I've found quite a few listings indicating commercial / industrial versions and applications for the tall-deck 427, which indicates it, too, was not originally intended for highway use, but was adapted. Several different water pumps were used, and several different head castings (some of which interchange with the more common Mark IV big-block Chevrolet.