We have the same problem
The mainsheet stand-up blocks on our 82 H27 also need replacing. I have searched, as did our marina, with no sucess. (Thanks for the lead, Benny.)We considered the traveler alternative. I have seen one H27 with a traveler mounted over the companionway in about the same position as the current mainsheet rig. In discussions with those who have more experience I got a resonse, "why a traveler, you don't race, and it is more expensive." Dan is correct that it should point better (there are other factors to consider) but do you need it to point better? I like the relative simplicity of the block system. As of right now the plan is to add block rehabilitation to the winter projects.AndyBaroque