Sorry to hear the downside notes, but you have the right idea and motivation. Knowing that it comes from a
'good family' , blue book sounds o.k. to me.
Good Luck in the new year and post your result!
p.s. blue book for '83 300 CD TURBO IS 6475 GOOD SHAPE RETAIL and 8150 for excellent shape. This is from a 1998
blue book so you are in the ball park fer sure. The leather seats add to value.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD