Buddy bottle regulators

I have a 4500 psi 68 ci bottle without a valve/regulator. Plan on buying a regulator for the bottle. Have to decide on a regulated output or unregulated output. I'm used to filling from a 66 cf unregulated tank.
How accurate are the 3000 psi regulated regulators. None of my guns require over 3000 psi. I do. on occasion, fill to less than 3000 psi.
Need recommendations on which valve/regulator to buy. Don't seem to find many available.