Based on what is available, there were 1,107,718 Mustang II's made. Subtract the 385,993 made in 1974 that didn't offer a V8, and you have 721,725 cars. Multiply that by about 20% (my guess) that came with a 302 and you have 144,345 over those 4 years.
Probably about 37,513 were made in 1976 with a V8 if one in five came that way.