Rim and Tire for a Duster?

I have this '72 Duster I want to upgrade my wheels on it. Currently I am running 14x6 4" BS with a 205x70x14 on the front and 225x70x14 in the rear.

I want to put some bigger tires in the rear and upgrade to a 15x7 in the front and for the rear I was looking at a 15x8.5 both with a 3.75 BS. I

n addition, the read has 10" drum brakes, the front is running a 11" disc brake. Will this run any conflicts to leaf srping location. I don't want to relocate anything or tubb it at all... Thank you for your input.