I converted a 30cc Homelite and it came out to 4.25lbs with the flywheel. I estimate the thrust at 12 lbs. I pulled a Poulan 46 out of a Farmhand 2750 and without the flyhwheel or coil it weighs 3 lbs 1oz. Thrust is estimated at almost double the Homie. It seems the weedie conversions just aren't worth a darn but if you go up in size a bit like to the 46 you double your thrust and get into a high power/weight category.
I can get that $135 engine converted for another $160, including a battery and switch harness, electronic ign, mech advance, prop adapter etc. If you were going to put the engine on a high lift high winger I'd say the flywheel's extra pound wouldn't hurt, but if you want to do aerobatics go electronic ignition on the conversion. That darn flywheel is WAAAY up front and will be hard to counterbalance in the rear.