I had a 64 1/2 Mustang coupe in 1974 (bought of for $300). It had the 260 V-8 and I bolted a set of stock 289 heads, Edlebrock dual plane 4 barrel intake and a Autolite 4bbl carb. Ran well, no big difference until i
I put the 4.11 gears in it. That's how I learned about the the proper torque sequence on head bolts, by doing it wrong the first time.