1969 Impala question

[x44d80]

I ran across what appears to be an original 69 Impala SS for sale today. It's a "run hard put away wet" car but could be saved. It has front disc brakes, Big block 4-speed non-air car some rust in the front fenders, quarters, looks like most of the interior is there, also has 427 badges on front fenders, needs a complete resto. No price on the For Sale sign. What do you look for to see if its an original big block or SS car and whats an approximate fair price to offer for a car that needs alot? Thanks Brent.