I found this today, I don't know if you have ordered your front end yet. I thought is was cool as it shows what the measurements are for springers. I know you are using that shovel to get an idea of front end length, this might help in getting the exact length you want when you do order it.
All springer frontends are individually made to the customer's bike for the correct length, rake and trail. Thompson Choppers springer forks are all manufactured in-house to order