That's why Ford changed it in 1930.
In designing machines its fairly common to add a non-threaded 'lead in' section to help with part alignment before the threads engage. Ford didn't do that
You could machine a 'lead-in' into the cap threads, but I'm not sure how many threads you have available to remove for that purpose. The lead-in would have to be a smooth 'slip fit' over the tank threads to work properly though, and the threads on a standard cap may already be cut to deep to begin with.
Or, you can machine out all the threads from a standard cap and make a new threaded insert with a lead-in. Yeah, that sounds cheap
Or, you could trade your car for a 30-31.
Or, you can be careful with your current cap
