Firstly.....welcome along to the club.
25mm is fine without any mods to cables....although the throttle may only just be a hint tight, and you can re-fit the bar covers......a 35mm film canister does a nice Job with the bottom cut out of filling the hole that's now above the ingnition barrel to your bar cover.
Hope that helps
Feel free to drop into the Introduction section and introduce yourself to the members.....you will always get a greater response to your enquiries by giving just a little of yourself