" Now all we need is a 6” BL howitzer or French 75 to go with it!"
IBG has a couple kits of the French 75 in Polish service coming out. I don't know what it would take to back-date them to WWI, but it's a start.
Quite a lot I’m afraid, as the wheels, tires, axles, brakes and gun shield would all need to be replaced/ modified to represent a WWI era ‘75. But I’ll bet somebody will produce one in the future, now that all these WWI vehicles are hitting the market.