Ride height 68 Valiant

I am nearly finished with my rotisserie resto on my 68 valiant, I want to order new leaf springs from ESPO, my car is a 340 4 speed so I will order the 6 leaf springs. I have a 245 60 15 in the rear and want the wheel opening and the top of tire at the same height. The car originally came with 13" wheels. From research and other pics I believe I may need a 6 leaf +2 to achieve this. If anyone here has insight on this or has done this same thing I would greatly appreciate your advise. Trying to get it right the first time.
Thank you!