SInce you are in Portland and the car is in Napa, CA, it is worth the drive to look at it before committing to a sale.
You could come to the Cascade Cobra Club meetings also and talk to owners of many different manufacturers' cars and get a feel. If the weather is good a lot of the guys bring their cars to the meetings and you can take a look at several different styles and manufacturers cars. We meet at Landmark Ford the second Saturday of each month. Watch for the schedule at
www.cascadecobras.com
I've looked at the Shell Valley cars several times. They are pretty well built and designed cars but a couple things I've noticed about them- the footboxes are extremely small and the tunnel is so wide that the seats are quite often canted in their mounting so they don't set straight ahead.
Also, keep in mind that 460's are very heavy engines- quite a bit heavier than the 427's and much heavier than a small block. Gas milage is pretty abysmal with most of them also. I think most Shell Valley's come with a 15 gallon tank, so your cruising range with a tank that small and the expected gas milage is pretty short.
Just my 2 cent's worth....
Bob