I've had personal experiences with sport coupes over the past several decades. Here's what I can tell you: They were low production because they were not popular. Starting in 1950, GM began producing hardtop (pillarless) vehicles. By the '60's, "coupes" were donsidered dowdy. The Sport Coupe was the lowest cost GTO you could get, and it came standard with 3 on the FLOOR. With a HURST shifter (Ford made the gearbox!). The post cars were and are much stiffer/stronger than the hardtop cars, and made good drag cars due to lack of body twist. I have never seen one with a convertible-type boxed frame. I would think that the drag racer would want a light, stiff car....not a heavy one. Also, drag racers back then ran 4-speeds or hydro's or powerglides, etc. Almost never 3-speeds after about '62 or so. My experience is that sport coupes are more solid, have less wind noise, less water leakage, and just feel better going down the road than hardtops. They look a little strange, sure, but they're great cars. It sounds to me like you found an original, base-optioned survivor car. If you like it, go for it. Post cars typicallly bring 20-30 percent less $$ than a hardtop car. As a PS, I work with two different guys who bought NEW high perf Chevy's back in '69 and '70....BOTH cars were 3 speed stickshift cars instead of 4 speeds...I asked them why, and they said that the extra $$ for the 4 speed (about $200) back then for a $2--2.5k car was huge....they simply could not afford a 4 speed, working at the gas station and going to college, etc. So, I think you have the GTO equivalent: a young (poor) buyer, buying all the car he could with the money he had. Sounds like a neat car to me!!!!