Weld Wheel Backspace 69 Barracuda

Long story short, my shop got broken into and my 1969 Barracuda got stripped. I need to order wheels for it asap so I can get it rolling again, but my wheels are gone now so I have no idea what size to order. I know they were Weld Prostars, 15x3.5 fronts with 1.75 backspace and 15x8 rears, but I'm not sure of the backspace. I know they had 255 MT Drag Radials. It's a stock 8-3/4 rear end. From what I read 15x8 will need a 4-4.5 backspace. Can anyone help out? Thanks.