Tire size problem

I think I posted this in the wrong place so here it goes again.
My 65 Mustang is being restored and is about 2 weeks away from completion. I put wilwood power disc brakes on the front.
Going with 15/7 Magnum 500 wheels. My dilemma is the proper tire size. My restore guy says to use 215/70R/15. I’ve read that size might be too tall. I’m leaning toward 215/60R/15. He says that size is too wide. I have kept a stock suspension. I really need help on this issue. Thanks in advance

Thanks that’s a good idea. I found someone that lives close that has the same tires and wheels that I am interested in. Going to try them out when the engine goes in.