Up to October of 2012, I used to be the Southwest Region Rep for The Victory Motorcycle club, and am currently the Northern Ride Coordinator for the Wasatch Victory Riders. I have never tried to build my own bike, but I used to always want to. That ended after I talked to many people that have built there own bike and were very disappointed with the end results. They put so much time, money, and effort into building what they think is their dream machine, only to find out that the HD, Vic, Star, whatever bike they had before they pulled it apart, cut it up, and put it back together was the one they truly loved.
Do you remember that episode of American Chopper where Senior buys Junior a big HD bagger for his birthday? That really set the message home for me. Why would one of the most well known bike builders buy a production bike as a gift or want to recieve such a bike as a gift? Because the bikes that they build are great to look at and brag about, but they kinda suck to have to ride on.
I think the trick to building a really good custom is to make it look like what you want without changing the ride quality that the manufacturers spend so much money R&D'ing when they built the original.
I have ridden a few good quality customs and have gotten off of them thinking that they were lacking, at least compared to my Vic.
Now, having said that, I wouldn't hesitate at all to take a Victory Jackpot and turning into one of these:
A truly custom look without having to alter the factory handling and geometery all to much.