To preface, I would prefer to use each of the two amps you have as the driver and be able to select between them (to have the benefit of
the tone core of each amp in play and have that drive the wet section of the rig), and use a stereo power amp for the wet side of the rig (or mono bridged for w/d, instead of w/d/w), as opposed to using just one of them just to drive the dry, and having the other drive the wet-- mainly because I prefer-- if using 2 amps (heads) to run the wet through a loop return of the wet amp, instead of through the front.
Suhr Line out box, is the 1st thing that I would consider, if it were for me-- (one on each amp), then there is the matter of addressing the effects being fed from each amp (as it's-- the amp-- selected). For that, a "Good" amp selector, is the next thing. Then perhaps, as has already been suggested a Suhr MiniMix2.
Egnater, CAE, and Skrydstrup R&D are the one's I prefer, but not cheap (unfortunately), but they are the only ones which allow for each amp to have a load on it while NOT in use. (Safer than some of the alternatives, and they have individual line level controls for each amp)-- (Unlike most/any of the others).
Then there is the power amp for the "Wet" side of the rig... My favorite is the Mesa Simul395, there are others.
http://www.suhrguitars.com/tonetools.aspx
Hope this made sense, caffeine hasn't kicked in yet. lol
Gotta agree w/ Mike, re: the RJM gear being great too.