I think that's about the right price for that card, given the market for "Authentic" Planks -- and represents nearly a $3,000 increase since what is probably the same card sold in Mastro's April 2007 auction, click this link:
http://www.legendaryauctions.com/Lot...px?lotid=73368
Coincidentally, in the same April 2007 auction I purchased Lionel Carter's beater Plank, for just a hair over the price of your restored Plank. So, I think that Plank collectors are just about evenly split on whether they'd rather have a beauty restored or a beater original.
If you tried to restore it you would have to remove at least some of the blue from the background, which would put you into SGC 30 value at best. And there is a meaningful probability of an SGC 10 or 20. As a result, I would recommend just leaving it alone and consider it in value as about what the market would value an SGC 10.
Most of all -- enjoy the card!!