Its hard to know for sure. Maybe 10.5D would be more comparable to 10E, but there is no exact science involved, especially across different lasts. How do the Indys fit in terms of length, width of the heel, width of the forefoot? Snug or roomy in any of those places? Not uncomfortably so, but if you were able to change the dimensions a little, are there any places that you would want it more or less snug?
If your looking to buy another pair and haven't settled on a specific model yet, check out some shell cordovan, if you are open to that kind of thing.