Filling CF tank

Well dropped of the tank this morning, P/U just now.
Here is the problem, with a din300 valve on the tank, which I have, they can only fill to 3700psi 🙁 🙁 🙁
They have the ability to fill to 4500psi with a fire house valve on the tank.
Jocko, thats his name, down at the scuba shop is willing to switch the valve for free. Being a dive shop he can use my valve, and I could get 4500psi 😀 😀 😀 😀 😀
My dilema is converting my fill assembly to the fire house valve.
So if any of ya guys know what I am talking about, what would I have to do to convert my hose assembly.
I know there is a scuba to fire adapter, however Jocko doesn’t like that idea, quite frankly I don’t think it’s a good idea as well.
Your input on this is greatly appreciated

SAW.