You didn't look hard enough. GT-2000 is an older model that's no longer in production. You can download the operator's manual here:

http://www.echo-usa.com/oot/docs/GT202400ES_021901.pdf

The engine is an older version of the currently 21.2cc. i have an Echo blower with this same engine. It isn't as strong as the slightly larger bretherens like the 23.6cc and 25.4cc, but it weighs pretty much the same. This means the power to weigh ratio is not exactly spectacular. Still, any Echo is a far better engine, and will come out lighter, than the likes of Weedeaters and Homelites. If you keep the magneto ignition, you'd be looking at floaters like 1/4 Cubs, GP PT-19, and Senior Telemasters.

BTW, Mr Pipercub, looks like you put your prop hub on what I'd call the "back end". I have no doubt it will run fins as is, since these engines have crankshaft center sections that are symmetrical either way. I usually put the prop hub on the flywheel side and remove the "excess" framework to save weight. Looks very well done though.