Jim, yes I have stock Spring Air gear, wire mains and modified Interco nose oleo with BVM sport wheels all round... It must be something to do with the heavier wing loading with bigger/heavier engines that causes the potential problems with bounce on landing, I have read about this quite a bit from guys flying the MB with P-80 and bigger engines installed. Personally I have never had even one bounce or any problems whatsoever with my MB landing too fast. I think the 'hopping' scenario comes from having to land quicker due to obvious higher wing loading and having to use the flaps to try and slow her down..... as I said previously my one lands so slow with T-500 I do not need to use the flaps at all, even with the smaller engine she moves out nicely at around 140 mph.
If you do plan on modifying the mains at all I would suggest removing and modifying molded wheel wells and getting hold of some trailing link oleo struts for mains as well as nose this would also assist reducing landing bounce concerns. If I was building a new one I would definitely do the main gear mod adding oleos that will fit as well as the nose oleo mod... I don't see how actually moving the main gear location would be of any benefit???