Internal gearing

Considering the fact that you will still need a rear derailleur to tension your chain, it seems a bit of a waste. The SRAM hub with internal gears plus a splined freehub seems a much better idea because you can nix your front derailleur.

On the other hand, if you already have the components, why not just try slapping it together and seeing if it will work?

I just recalled something important from my own conversion project. The chains and sprockets used by derailleur bikes are narrower than those used by cruisers and internal gear hub bikes. I had no problem with this because I purchased a cheapo 22t sprocket for my shimano hub. The sprocket was made from thinner stock and fit my narrow chain without problems although it wobbled on the splines of the hub. I do not know if special sprockets are available to help you with your conversion but I have tried derailleur chain on normal sprockets and it doesn't work. The teeth wedge into the chain and stick.

Also, the rear spacing had to be narrowed. If you have a shimano 4, 7, or 8 you already have standard road spacing, 130mm.

Last, the derailleur interfered with the rear sprocket. It was designed to clear a much LARGER sprocket than the one I had, but only when extended away from the frame, closer to the centerline of the wheel.

As an aside, I would add that if you have an internally geared bike you are not happy with, try screwing around with the rear sprocket first. You may find room for improvement. I favor older equipment (see sign-in name) and back in the '70's bike makers seemed to think 20-30 rpm was ideal cadence. Adding teeth to the rear sprocket really livened the bike up and made it usable, but I still can only use high gear when the wind is at my back and I am on a slight downhill. I would tailor it down further if I could; not being able to barrel down hills at 25MPH on a 30 year old bike is a small sacrifice.