Aegis21,
Sorry, started watching football and didn't see your return question til just now. The direct answer is that most any roundhouse can be made to work with any turntable without significant modifications to either product. The only exception that I am aware of, in O gauge, is the Atlas table-top turntable which requires whisker tracks to line up with the turntable in certain positions. In the Atlas case, you either have to find a roundhouse that lines up with the turntable positions, cut off the turntable position blocks, or use flex track to meet the table at the required positions and then adjust as it enters whatever roundhouse you choose.
The most complicated aspect of RH & TT use is the amount of space you choose to devote to that use. All the math involved in the choices (size of TT, size of RH, distance between the two, etc.) is a function of maximizing your use and enjoyment while trying to make it look reasonably accurate. With that, I hope you have a successful build.
Chuck
