I take it you are talking about the push rod between the camshaft and the mechanical fuel pump. Well my dad had to replace this on a Gamine at only 6 months old. The problem was with high revs going up steep hills the engine would slow down until the carb filled up again, usually on the downhill or the flat. There was also talk on the 500 club of others suffering excessive wear to this rod. My dad replaced with new and all was well, this was 40 years ago. To remove the rod remove the pump and distance piece, there should be enough sticking through to pull it out. If you can establish the amount of wear you could machine the spacer to accommodate the wear or as you suggested replace with an electrical pump, remember to fit a cut off in case of a collision.
Ralph