If you have already decided, cool.
I ran a V3 a fews times behind my mics, deciding if I wanted to upgrade the mics or pre/ad. I personally decided I needed to upgrade my mics first. (I liked the 391's well enough, the 393's were too bright for me). It sounded better then my regular setup no matter how you slice it. In any event I liked the sound of other mics>BM2P+UA5 better then the pre-ad upgrade with my existing mics.
The single box solution is apealing though.
Depending on budget, a 140/50 active setup?
Guess it depends on if you want different mics or a different pre/ad/recording solution. Sounds like you want the latter, and everyone seemes to agree, I decided in my limited experience that I wanted to move the other direction and upgrade the mics before the pre/ad.
I guess it all depends on what/how you tape though.
Good luck with the upgrade.