you folks are awesome- thank you!

Believe it or not, in the midst of all these replies, I have found an answer to my question.

... and yes, i agree: its advice, not advise. Thanks for correcting my typo.

I was looking to spend my money more wisely on this next one. I figured there are some details that are more important than others & building a car specifically to sell at auction is a business gamble like any other: people want customized old cars, just like people want hammers, because pounding a nail with a rock sucks. Some hammers sell better than others. Why? That's a good example of the nature of my query.
I get that there are no surefire recipes in this billion dollar business. but there are trends, likelihoods, and really bad ideas.
Someone replied earlier mentioning that a buyer has to "share your vision".

Brilliant!


Within this idea, I can see that the salesman has as much to do with the final cash paid for a car, as does the "theme" of the customized car itself. Thats why I was targeting auctions. For 18%, they've already done all the marketing. Dialing in the Theme of the cars custom features with an idea to attract the largest possible pool of buyers for the specific year/make/model of the car in question, well, thanks to you folks, i have a better idea about how to approach it. There are plentY of avenues for discovering the final value of a restored, stock old car. Its much more tricky with a customized old car.
To the one that encouraged me to continue keeping an eye on the auction results: thank you, i will continue: Because at auctions, people are seperating themselves from their money by the millions for vehicles of all kinds, and usually in the same amount of time that it takes me to pour a cup off coffee. Its a huge, vibrant market place, and if one plays their cards well, they can make a little coin in the middle of it all.
Generally, I think most HOT RODS are the result of individual "gifts to themselves". and thats not at all what i was inquiring about.
I had an idea for a theme on this old hard top in my driveway, and i wanted to learn wether if it would add value to the car, or diminish the value, using stock restored value as a standard. Hard call, I know... But i think i have a better grip on it now.
Again, thank you for all the input!