Hi and welcome to Ireland!
It's weird that you require some changes for generic jedi, in general SG standard are very close to RL one. Anyway about boots it's always a pain. I got mine from ebay and they are polo boots (from the sport) but in general US army from WW2 should be the correct ones. About belt and belt ornaments jedi-robes might be a good cheap option. For the tunic unless you feel comfortable sewing it yourself, i would suggest to check the main legion forum in the trade/sell section. Maybe someone else might suggest a tailor/seamstress.
Cc: @TigerJedi if you have any other suggestion.