I was assembling the conversion kit and was doing fine until I tried to mount the handlebar stem. I have a Wally World new donor bike, but couldn't figure out how to mount the handlebar stem. The adapter listed in the instructions and included in the kit won't fit into the hole in the fork. What do I need to get to mount the handlebar stem at the correct height? I took the kit to a bike shop and they couldn't figure it out (not much help). I'm at all stop until I get some kind of part for the bike shop. I can't be the first person to try to modify a cheap mountain bike, but I can't find any info about getting a proper stem extender. Please help!