The net result was I ripped the old models off their base and extracted the barrels with minor damage then reassembled them as 152mm guns instead. Then a repaint job on the guns and a tidy up and texturing of the bases. Net result two 152mm guns up to my current standard.
And the 122mm's? They are now assembled (very easy) and painted, but the crew will be painted along with the rest of the Russians in the queue.