Actually, I regularly (now) see Janpol 80 mm lenses on eBay with M39 threads that should screw directly into many/most modern enlarger lens boards/tubs. And while I don't speak from experience (I have a 105 mm Vega, an apparent Russian copy of the Janpol, but the magenta filter is badly deteriorated), based on the glass size relative to common lenses the same speed, it looks to me as if the optics are compensated for the filters (which ought to mean normal coverage for the lens size, i.e. 80 mm covering 6x6), and with the filters well away from the plane of the aperture there should be little change in filter effect at reasonable apertures (say, for the f/5.6 lens, through f/11). Seele, have you actually found the problems you indicate from printing with the lens, or just heard about them (and if the latter, from what source)?
Eumenius, coverage limitations should be immediately obvious, if present. I'd suggest there's a cheap way to check the filter issue -- use the yellow and magenta filters to print on multi-contrast B&W paper, and watch for contrast changes with changes in aperture (with, of course, compensating change in exposure time). If in fact the filter effect changes as the lens is stopped down, you should see a reversion toward "no filter" grade (2 or 2 1/2 for most papers under tungsten light) at smaller apertures with small amounts of filtration, but a trend toward more extreme effect at large filter settings. And of course it's much cheaper to test this with B&W than with color paper and chemicals...