[Rory McNeil]

The 70 351C 4 barrel engine is not a very good combination in Stock, and likely Super Stock either. The 70 engine is rated at a higher HP than the 71-72 351C 4 barrels, and have a considerably smaller camshaft, which isn`t an issue for S/S, but the carb issue certainly is. Where the 71-72 is allowed to use a Holley 780, the 70s stuck with the small (480ish cfm?) Autolite 4300.
So less cam, smaller carb, and at a higher HP rating, not very surprising that there are numerous 71 and 72 Mustangs with 351C running in Stock and Super Stock, and some 71/73 351Cs running in the SS GT classes, but I can`t recall anybody running the 1970 version, in a number of years.