Will 15" rims with 3.5 backspacing fit my 69 Baracuda?

I Have A 72 Duster With A 8 3/4 Rear End Stock Leafs. I Have The Largest Wheels On My Car That I Can Put On With A 7 Inch Rim. 245/60 And Fronts Are 215/60. Hope This Helps In Making Up Your Mind. 15 Inch.