hi joe , regarding the rusted piston prob. ive found that thereino easy way... however you may like to try amethod i have successfully used onlarger motors, that is position the motor so as the cylinder is in the vertical pos.ie.barrel facing up . pour in some kerosene , or if you are not financialy challenged wd40 now get apiece of soft wood small enough to fit into bore & give it a few GOOD whacks with a large hammer, the shock seems to do the trick. however if the piston is in the bottom dead centre (bdc)or the top dead centre (tdc) this metod will not produce results,
good hammerin john

i may have retired but i havent stopped yet, ive got one shed full of woodworking machines & hand tools(my other love, makin sawdust)my othr shed is mechanics tool chests stick &mig welders metal lathe 9 inch swing screw cutting so if icant buy it i make it,i hope im writing this in the right place,thats all i can think of at the moment, cheers & beers