Yes, those 6-cylinders are OK for the shows. For us, Mustangs are a family thing. We've got the 289 in one of our '65s, and the 200 six in the other. They've both got their places. My favorite is my red 65 coupe with the 200 and manual three-speed. It's snappy, cruises great down the Interstate, and doesn't eat a ton of gas. It's the original engine to the car (I've got the original window sticker) so yes, it's definitely a Mustang, despite any comments by V-8'ers who don't get it!
Overdrive