Kadesh did not happen during WW2 but afterward. It basically was a conflict over the Suez Canal.
A new terrain is in progress for it that covers Egypt, Israel, eastern Med to some extent, etc.
We have also looked at other ideas such as the Soccer War in central america where P51s and F4Us face off versus each other in a conflict between Honduras and Guatemala in the 1960s. Back burner idea since we have to work on central america terrain (in progress but others ahead of it).
Also there was the Israeli Arab conflict that used Spits on Egypt/Arab side and 109s on the Israeli side.
As for substitution .. well even in the WW2 scenarios hate to say it but have to do since we don't have complete plane sets for all the parties involved. Russia is lacking many planes, Italy, Japan, then early war entries of france, Poland, etc., etc.
We have to make do with what we have in many cases. And basically seek what can be done to create an event that players will be interested with what we have .. making close substitutions when possible.
To let you know there is player interest in this so far since its a player designed event (not a CM one) where the player approached us with the idea, the write up, even a working terrain, and asked us to consider it to be run. So we are working in partnership with him on it.
If your not that is fine but if we had to get 100% of everyone interested in an event then we would never have any. You just don't play in the ones that you are not interested in. Personally, I was not interested in Niemen. Nothing wrong with it .. just did not hold an interest for me. The people who played in it thought it was good by all accounts.
There is significant interest in it, it was submitted to be run, and the player is working through the process of how to setup the event, etc., etc. with the CM staff.