Don't do it!
I got an afternoon on a Whyte 19 with Sram something on it. Very nice and fast but felt a bit out of the loop. I bought another RC200 to stop me spending good money on new things.
I did write up a spec for a new bike involving a Pace 303 frame, RC31 forks, lots of hope and XTR. I realised the amount I would spend would get me a fleet of awesome retroness... So ditched the spec sheet.