If you have done a belt, i would advise replacing all the pulleys, especially the drive pulley on the layshaft
I'm not sure if you run a roller next to the drive pulley to stop belt skip? If you dont, then just make one up from old parts in your box.
I also run the twin rollers and the longer belt but im not sure how much this helps to be honest. I never had an issue with the single roller till the euros
