While soaking in acetone, fill tank with small metal parts (¼" or smaller nuts, bolts etc.) and shake it up. Let sit overnight and do it again. Rinse with clean acetone. Might take a couple of cycles.
If done correctly, inside of tank will look factory new. Hard part will be cleaning fuel pick-up. Use acetone on this and fuel line also. Take your time. If destroyed will be almost impossible to replace. Treat it like you've discovered a one of a kind dinosaur.
Don't soak carb in acetone. Disassemble and soak/clean with kerosene. Blow out.
Note that these engines had no kill switch. Choke it to stop it.