What about Leopards as main battle tanks? I don't think it's too far out of the picture given the fact that lots of smaller countries seem to operate them. They're also a bit more modern than Chieftains, and while North Point would not really focus on MBTs as much as other things - I think having them upgrade to Leopards in the 90s is reasonable. Considering the Challenger 1 as well. But big chance I'll just stick with the Chieftain.
That said, is it even worth bothering with tanks? Why not have an entire army of Land Rovers with anti-tank launchers?
I bumped this thread with the intent of reworking the navy, but don't mind also focusing on the ground forces.