$1500 less $1 for each mile you have to travel to pick it up, so -$500. Seller pays you $500 to haul it away.
From just looking at ads on Crag's list Los Angeles, prices seem to $1500 to $3500. I can't imagine paying more than $2000 for '87 with 53k miles.
Unless it has new tires, replacement (rebuild-able) rear shock, I would think $1500 for working mostly clean bike (ok paint, no tears in the seat, ok tires, NO DMV back fees) is fare.
If you pay $800 that leaves plenty of money for the U-Haul to get it home if it dies on you. After all $800 is more than $1 per CC.
Good luck.