I have a 1970s Huffy built three-speed bike with a Shimano 333 twist grip shifter and matching handgrip on the non-shifting side. The stock grips offer minimal cushioning. How can I add cushioning and retain the original twist shifting mechanism? Would a foam grip expand enough to fit on the 31 mm diameter shifter? The non-shifting handgrip is approximately 28 mm in diameter. Maybe cushioning tape over the shifter and the non-shifting grip? Thanks for any ideas on this.