Yes but .

I'd let the KROIL (great stuff BTW ~ it beats Gibbs and all the rest by a HUGE margin , try it ) soak for a few days , if you lean the Moto over to the left , it'll retain more of the mix in the cylinder .

Time is hard to allow when you're playing with a new project ~ I know this .

As the piston is far up in the cylinder you can always remove the head and use a block of hardwood (bits of old pallets behind some whse.)  and a dead blow mallet to knock it loose .

Me , I'd let it soak a few days / week then remove the alternator cover and ever so *gently* work the crank back and forth , back and forth with a 6 point 14 MM socket on a flex handle (misnomer : 'breaker bar ') , if it's ever going to come loose and allow re use of this piston , it'll begin to move in tiny increments , do not force it , rather keep working it back   & forth , forth & back , always adding more solvent (ATF is good too) until in time you can rotate the crank 360 degrees , then you can set about tuning it and seeing if it'll run and how well .

Typically once freed up they'll run great but might smoke depending on how bad the rings & piston is .

85 ~  90 % of the time , a new (and cheap BTW) piston and rings will set everything right again , not often needing boring nor honing , just clean that cylinder HOSPITAL CLEAN .

I miss resurrecting dead Motos and have quite a few under a tarp in my back yard , looking forward to getting back to working on Tiddlers when I retire this November .

TAKE PICTURES ! we like to see =8-) .