4-53 is too long. I ran into the same problem when contemplating a GMC 360 (similar to the 477/503). As the doghouse butts right back against the entrance, I'd rather not have to push it back much, if at all. A 3-53 or 6V53 is about the same length as the Stovebolt.
Weight? Eh. It's rated at 10,000, has a curb weight of about 5500. Front axle is the same one used in 1 1/2 and 2-tons. It'll take the weight. More so, if I can locate a lightweight military version! I still have friends in TMO and DRMO! I'd definitely need power steering, however.
I'll throw a pic of the engine bay in, so y'all can see what I'm working with. The width of the 6V would require some sheet metal work. 3-53, and I'd have the same problem I have now: power. 150hp out of a 3-53 is doable... And so is 200hp from a 261. 6V53 silver series had factory ratings up to 350hp! I'd be happy with 200-250. Thus, the 261, my GMC 401M, or a 6V53.
I'm still learning towards that 261. Bolt-in fit, and it'd look right at home. The 401 would be neat, and that Detroit scream... but I love a Stovebolt.
Have some more pics:
If a 'truck' is only used to haul butts to the mall, then it's not a truck - it's a car with a roadster trunk.
Old, rusty and ugly - might be me or my fleet. You decide!