No offense, but any kind of conversion, like you are talking about - is not likely to end well. Because of all the new countries, Anzac, Italy, France. New Pieces as you mentioned, and new map.
Seriously, for all the work, energy, material, and investment it is going to take you, to try and make a game of Global out of 1942 and Classic. There is a MUCH better approach.
Get a part time job for a week at McDonalds or whatever, after 15 hours of work that’s roughly $120 - enough to buy the game.
That or you could pick berries on a farm, go haying, deliver newspapers, or sell vacuums door to door or whatever, even temp in construction. There is always some kind of oppurtunity for you.
Your conversion is going to take WAY longer than 15 hours, and it won’t look as good, plus once you have this job that you don’t care about, if you like you can keep it a little longer if money is a consistent difficulty.
Even collecting bottles, or mowing lawns would be easier, than attempting this conversion.
Money is what makes the world go around.