RE: Craftsman 25cc Conversion
I've had one of the 18cc engines set up for gas/glow at one point before I found out there just wasn't enough compression to run (scored), but with prop, prop adapter and everything needed to run it was right at 2lb. The 18cc engines are a little lighter than the others though, the cylinder on the 18cc is a different casting than the rest of the sizes, I think there are only two different outer castings but I have never looked at the rest of the sizes that close, the crankcase on all of them is fairly similar (there are a few that are slightly different, mostly back plate seal wise)
The GTI 15T are reed intake rear exhaust, I've got a few of those too.