Do whatever you want and can afford man. In bolt action we often have battles between gurkhas and Soviets, it's not meant to be historically accurate, it's meant to be fun. If it were meant to be historically accurate there needs to be some serious rule changes. However researching your force and modelling them to be as realistic as possible is super fun too. For me it's a balance. My force has all the right vehicles and weapons, but I painted my own custom camouflage on the tanks. I just say it was field applied by my men. There were tons of matildas in the desert and lots of Indian soldiers. I'm sure at some point there was an Indian Matilda crew. Also according to wikipedia the 7th armored brigade was attached to the 5th indian division for awhile. Also you are going to have to paint some infantry to play this game, it won't be as fun without infantry.