I picked up a complete MS291 for sale in a box completely disassembled because the piston has a hole in it, for $50 today. I want to put it back together. I was looking around for parts I'll need to order and I saw some posts about upgrading an MS290 to MS390 by replacing the entire short block. I've rebuilt some lawn mower engines, but this would be my first two stroke rebuild so I'm learning something new with this project. Are there any similar "repower" options for the MS291? I don't really see any but I wanted to ask here. I'm like Tim "The Toolman" Taylor, more power! The MS291 would be fine for what I want to do with it, but since it's torn apart and I have to order parts for it and there's an upgrade, I might as well do it.