That's one big mambajamma. (A mechanics point of view)
R-4630s would be a huge pain to work on. I have spent about 4 and a half years restoring and maintaining WWII aircraft, and with a 2800 Double Wasp it was a chore just to R&R and test the plugs (an A-26 or F7F has two 2800's with 18 cylinders, two plugs each for a total of 72). With six 4630s, you know what you'll be doing for the rest of the week!
It takes a whole lot of time for such a trivial task...
Oh well, I kind of miss working on the auld beasts. although I've never seen one of these!