Thinking about getting another bike for this year and tried my 2 piece leathers on and not feeling very comfortable with them anymore :/

How the hell do you size 1 piece leathers? I see so many different options, or is it a case of going to a shop and trying a few on OR spending major money and getting a tailored set?

Also, bike wise, looking at an 200/2001 ZX6r/ZX636 or ZX7r