Personally, I converted a 68 cu in 4500 psi tank using one of these:https://www.bestfittings.co.uk/shop/airgun-charging-equipment/cylinder-accessories/mini-cylinder-vale-assembly-day-tripper-valve/I've been wanting to convert a 45 cu in 4500 psi tank and a 500 cc or maybe a 1L CF bottle... Just haven't gotten around to it. The kit I got seems very well made! I haven't filled it yet though
Did you order from this actual site ? How was the shipping ? This seems like a great way to utilize an old 68ci omega bottle, might be perfect for topping off the PP700SA ?