That was close to the year that Mustang started putting 390's, 427's, 429 etc. big blocks in them. ('67 was the first year for the 390's.) so yeah, you have room under that hood for it. But like was said, you may have to beef up that front end if you had a 302 in it before. I'm going to move this discussion to the Classic section since we are talking about a classic.