But all of that stuff is just what you need to do to build a low noise source!
Also, amplifier linearity matters (AM->PM conversion), and careful selection of crystal drive power level makes a difference, Leesons eqn. becomes very real when playing with that stuff.
Metal biscuit tins with battery packs and bulkhead BNC connectors are very much your friends for this sort of work.
-120dB sufficiently far from the carrier is **EASY** with a notch filter and a spectrum analyser, for all that seeing that close in calls for quadrature mixing method with careful attention to the control voltage supplied to the pullable osc (Noise pickup here can really screw you up).
-170dB, yea, that's going to be tough.
Regards, Dan.