1967 Value question. Help please.

[68hodaka]

Hi everyone.
New guy here.

I have a question regarding the value of a Chevelle.
I know that there are a lot of variables, but any advise you can give will be appreciated.
I'm going to buy a Chevelle in the morning.
It's a 1967 Chevelle Malibu with a very low mileage high performance 350 crate engine. The owner has put in a roller cam and some more high performance parts.
It was dyno'd at a tad over 400HP.
Turbo 350 with original posi rear end.
All new interior with front bench seat.
AC works great.
The body is in very good to excellent condition with no rust.
Louvers on the hood.

What is a fair market price for the car as described?

Please let me know asap.
I only have until tomorrow to decide.

Thanks for all your help.