I'd vote for a FM2 or FM3a. I played with my 50mm 1.2 ais on the EM body before. It was quite comical to look at and handle, the balance wasnt too bad, but it was all loaded up on the lens with the body being so light. The EM doesnt offer manual modes, but the meter was good in AE mode, and you could fine tune it with the back light button, or playing with the ISO dial. But the EM and the FG would be the smallest Nikon has to offer.
My 50mm 1.2 stays on one of my F3HP's with H2 or G2 focusing screen for low light.