For framing- the S-Mount and Contax RF mount 85mm lens works out better than the 105. The Amedeo adapter that accommodates the external mount lenses brings up the 50/75 framelines. The 75mm lines work out to be 100% framing for an 85mm lens at 6ft or so.
The price on the Nikkor 10.5cm F2.5 in Leica Thread Mount has dropped: I picked up a nice one for $200 on Ebay, could not pass it up even though I have one already. I use one for the M Monochrom and the other for the M9.