As everyone has said, it's just about how much money you want to spend. Any car can be made fast. Personally I love all Mustangs but the classics are just awesome. Get whatever body style you like best then slowly build what you want. There are more and more companies out there that are catering to those who want modern advances and safety in classic cars. You don't have to do it all at once either. When you finish you'll have something that's completely different from other cars on the road and it won't be any slouch either.
Just my two cents
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66 Tahoe Turquoise Coupe
Laser Red 96GT Ragtop
Both are slow but easy on the eyes!