I would suggest you bring your backpack Blower to you nearest dealer and have him advise accordingly . The New Blower Model 380 may be in the same chassis . He may be able to repair your unit or have another unit which may be a donor engine for your needs. If possible corner the Mechanic , sometimes they work on weekends and can supply reduced repair pricing on the side . Otherwise Ebay would be your best 2nd bet Dude !

Take out the spark plug and spray some Liquid Wrench or similar penetrant in the cylinder. Leave it soak overnight. See if it frees the engine up. This sometimes works if the damage is not too severe. In any case you have nothing to lose.

it might behoove you to try some good old coke (the soda). frees up things like no tomorrow. it is salvageable. dont leave the coke in too long or the block will disappear. if this doesn't work i have scene a graphite spray lubricant/ anti-seize, the motor worked first pull.