Yes, modification of the top cover is possible and there is a recommended method with dimensions to follow. Unfortunately I think you will want to do it with the cover off anyway. So it may not help you this time but if this is an ongoing problem it could really help.
I don't have the dimensions but remember them being posted here.
Don't forget to grease the pilot bearing
I pulled the cover on the top of the clutch and found the source of the squealing noise and the grinding gear problem. All four bolts holding the drive coupler together between the clutch and transmission input shaft were loose. This caused a snap on the clutch shaft to come off and it let the shaft move back when the clutch was disengaged and let the clutch disc come clear out of the flywheel. When I would try to engage the clutch the teeth were rubbing on the flywheel, play with the lever and it would finally slide together. New hardware and a little adjustment and it works fine.
Don't forget to grease the pilot bearing