Gran Comp hubs have two 2mm washers on the back axle.
Remove them and you are not going to have much problem.
However if it is the older dropout slot widths you will probably have to take a few mm of the axle with a file. Which again will not affect performance.
I had to do this with an older Jap bike once to get system-x hubs into the dropouts, both front and rear.
Worked fine and continues to roll with no issues.
Gran Comp hubs have two 2mm washers on the back axle.
Remove them and you are not going to have much problem.
However if it is the older dropout slot widths you will probably have to take a few mm of the axle with a file. Which again will not affect performance.
I had to do this with an older Jap bike once to get system-x hubs into the dropouts, both front and rear.
Worked fine and continues to roll with no issues.