let me tell ya i got a soft spot for retro cars with fins mm. any modern sport bike over 499cc's will pull at least high 5-sec 0-60s from the factory, so i wouldn't doubt it being engine swapped, seeing as it's probably not the best idea to boost the hell out of such an old engine to get that kind of acceleration, but i could be wrong idk know much about engines that old. def modded tho