you didnt get a bad deal unless that thing has zero compression. throw the dome o rings back on and compression test that thing then check the squish on it as well. sounds like the dude "thought" it was a 421 cub because it was a 420 bore, ive seen tons of people online say i have a 421 cub blah blah blah when they have a 421 driveline motor or an athena etc. anything that is 420 cc basically. maybe he was lying who knows, too late for that, anyways i can tell you this at least the motor doesnt have trinity PLUG LOCKS on it. Also that jetting might not be too far off. what "kit" did you order? and what needle is in it. I have a set of CEL needles id give you if you need some