how much would u pay for a '66 mustang, in above average condition, with new flowmaster exhaust, rebuilt engine 21,000mi, new kenwood sound system
289 engine
perfect condition of seats, and interior, light blue
Its very very hard to estimate a price with the information you have provided. If the car is in good mechanical, structural, and cosmetic condition as you have stated....a rough estimate...6500 or so.
Now, price will vary depending on where it is located, special options, how good the cowl and floor pans are, other modifications, rust, transmission, etc..