Never convert a secondary regulator for primary use. The reason for the LH and RH is so that the secondaries cannot be used on high pressure applications. Your best bet would to find a fitting that will convert from LH to RH. Only LH threads I am aware of is bicycle pedals.
If you are using low pressure in your cylinders applicable for secondary regulators, then you may be in luck.
Scott Zuhse, Instructor
Micro Matic Dispense Institute