Have ran similar car to yours for many years (70 Roadrunner alum headed 451 TKO 5spd) tried every possible bias and radial "street slick" day in day out 28 x 12.5 M/T street ET most forgiving (1.46-1.49 60 fts 11.20's 121mph) 13.5 rubbed on my car. If you really wanna have some fun get a Mcleod sof-lok and let her rip. Don't let any one tell you can't be used on the street. You'll never break parts and will be able to really realize your cars potential and get some consistent traction and go some rounds and have some fun. Bracket racing is way more fun when you're winning!