It seems here, he used a single speed pinion on a 2 speed tranny. The only way i can see that working, is if he locked down the second gear. That pinion isn't even on the 1st gear. So yes, if he locked down that second gear, then you will have mesh issues. An advise i can give you is, break the car down, check for wear, and put it back together according to the manual. Some one who locked down second gear to use with a single speed pinion is something that hints this guy does things half @ssed. I'm sure it's not something you want to hear, but it's the truth. Also, when you break things down, you learn how the car operates. If I were you, i'd break down all the driveline parts, and inspect it, like diff's, and rebuild it. There's no telling what this guy did, and didn't do to the car seeing that he rigged the car up. I also hope that you make holes in the body to allow air flow, if not, you motor WILL over heat.