I work for Akzo Nobel Coatings which is the largest paint manufacturer in the world. The Automotive Coatings trade name is Sikkens. I will tell you that you can get the Centennial Gold Paint Matched dead on.
I had one of he guys in the Techincal Department take a "Camera Shot" of the color to make me a pint to keep around. Well, they did and then tweaked it a very little bit. They then proceeded to do a spray out card (one with a hole inthe middle), when I held it on my tank, it was perfect. Let me tell you, 16 years in the Coating industry and I have a pretty good eye for color match.
I am not saying run out and buy Sikkens becasue I work for them, but you must use a quality coating, primarily one the uses LIQUID PEARLS not powder. The Valspar "House of Color" has received a pretty good name in the motorcycle industry, but I will tell you, the product is junk. They still use power pearls which are not conducive to match todays newer colors. Their product is so out-dated it is not funny, their coating technology is about 15-20 years behind what the major coatings comanys are doing today. The reason many bike painters use it is because they live from check to check and the stuff is cheap compared to Sikkens, DuPont, PPG, etc.
Do not go to a NAPA store, do not go to any other Auto Parts store and think you are going to achieve the Centennial Gold.
HD use PPG as thier OEM product line, so that tells you that they can match it with their assortment.
I will see if my Technical Dept stil has the final formula they used for me, if so, I will e-mail it to you and you can find a Sikkens distributor in your market (I know we have a company branch in Dallas Ft Worth) and get what you need.
Sorry to ramble.