You'll want a 3 to 3 1/2 inch backspace. With the 235 tires, a 7 inch wide wheel will be fine, 8 inch is about the limit for that size tire. I would advise against a spacer if you can avoid it, especially on the front.
Right on. The wheels I'm lookin at have an option for 3 1/2" bs. I'll go with them. Is there a reason for not recommending spacers on the front? I've ran them on many trucks before without issues. Is it just these old trucks?