I'm modifying a Gary Fisher Marlin GS for road duty. I replaced the flat bar with a Jones H-bar, this is ideal for my GF's preferred narrow hand placement, but requires shuffling the current Alivio trigger shifters way outboard due to limited grip end space (5.5 inches). I'm guessing a twisting shifter would be more convenient and solve some of the ergo issues we both have with those Alivio shifters, even when they are in the correct location. The drive train is an 8 speed triple, Deore RD, Alivio FD; is an 8 speed twisting grip shifter a direct and compatible conversion from trigger shifters? Any recommendations?

Another issue is the high gear. The current Bontrager crankset has a 42 tooth big ring (104BCD/4bolt), I would like to install a 48 tooth Shimano outside ring; any comments on that swap? BTW, I measured and there is clearance for the larger ring from the chainstay, FD is top pull clamp on, so room here also.