Here in mn, that motor fully tuned and cosmetically excellent would perhaps bring $600. Looking fairly beat as it does, $350ish after full servicing. If it pulls over w/compression, and has been sitting in the shed for years, $150 would be max.. Those prices are that high because ducktwins are fairly rare, and there is a market for ‘em.. especially with excellent graphics.
That said, if you really want a ducktwin, and it has good compression.. they are fine motors when serviced, but you could likely find a regular lightwin for much less $..