Well I don't have numbers right now, but most people aren't going to tar and feather you for modding a dohc. As long as you do it tastefully and do good work!
However, are you looking at the vin plate, or the stamped number, if it has 1? There should be a vin plate that says the vin, year and model. At least my 78K has all that.
The ride IS the adventure. The destination is just to get gas!