Spetsnaz, I haven't tried it, but I don't think that it would focus easily at f/2 on an R2 or Cosina would have made one instead of the 90/3.5. However, you should be able to use that lens & focus apertures wider than f/2.8 okay.
Erwin Puts suggests a minimum effective baselength of about 28mm for a 90/2.8, which is beyond the EBL of the R2 (25.1 mm). On the other hand, a Bessa R3a should be able to handle the 90/2.8 easily. However, the 90/2 would be beyond the reach of even the R3A. According again to Puts, the 90/2 requires an EBL of about 40mm; the EBL of the R3A is only 37mm.
Some alternatives in a portrait lens would be the Rollei 80/2.8 Planar - slightly lower cost than Leica 90/2.8, but it will focus okay on the R2 because of the shorter focal length - or the Voigtlander 75/2.5 Color-Heliar - shorter still, but compact & even faster.