Nice job, Leo. I have the same bike. I run a 44T, and had to spread the chain-stay to get enough clearance. Also, my engine's down-post saddle was small, so I used a mounting-kit. It JUST fits. I'm curious: is the seat-post saddle on your engine FLUSH with the post, or is it at an angle? Your down-post seems parallel to the lower saddle and this frame's angles wouldn't allow a snug fit on both saddles. If the seat-post saddle isn't flush I highly recommend that you make it so; it's the most important frame/engine connection.