Many people don't differentiate between the 1Ms and the King Cats. That's because there really isn't a lot of difference. The chassis is identical. Seat/tank/handlebars/suspension. Everything will interchange except the tracks and drivers.
Previous posters are correct in that the King Cats were all 3" pitch, 162 length stock. They didn't all have the attack 20, and many that did will have been changed by now. They did have titanium springs stock, although some won't by now, what with people modding the clutching and such. Especially where you say this one has a Paragon secondary.
I believe all 1Ms came with the speedo in the box, not installed. Many people (or dealers) installed them, some didn't. All 1Ms had the drop and roll on the chaincase, not just the Kings. They also all had the lightweight seat and clear tank.
Pictures may help clarify, I believe you can also get the VIN number, and a dealer can look it up and tell you exactly what it is.
I'd be more wary of the twin pipes than the fact that it's carbed. I like my carbed engines, although the EFI ones I've been around have also been impressive.
Also, when you say you have an '04 159" King Cat, did you change the track and drivers, or do you mean a regular 1M?