That's a very presentable model, and I like the subject very much; my compliments! To my knowledge, no Whippets were used in the Russo-Polish war, but I suppose that since a wargame is a game, you're free to use your imagination... I actually had the same plan to make a MK-V out of an Emhar MK-IV, but unfortunately there's more to change on the side panels then just entering a new piece with ventilation slits. Another possibility is to cut a part from the MK-V* from Cromwell. Peter Kempf has written a fine how-to piece on the Landships site.
Michel, the Osprey on the Red Armour suggests that this tank (A322 Stenka Razin) was used against the Poles in the Ukraine in June 1920. Nothing to corroberate it but for gaming thats good enough for me (I'm fed up of the Poles fielding FT17's anyway and thought I'd give them something to think about for a change)
I've started the MkV this week, even for a gaming model I seem to be spending a lot if time removing panels and adding new ones
I'll go along with the info if it comes from Osprey, even though I haven't seen any photographic evidence. Nevermind. I'm interested to hear later on who won in the wargame; the Renault FT or the Whippet....
Also looking forward to your outcome of the MK-V conversion. In case you're interested in more than one MK-V, I know plenty resin manufacturers who are interested in a master model, in order to issue a MK-V model in resin. If you like the idea, just drop me an e-mail.
) but quite pleased with how it came out. 
