Sir:
From what I can see the M37 factory safety isn't reverseable. I've one in the shop now so will check in the morning. The reversed safety buttons used to be available to alter safeties for left hand use but I haven't seen them lately.. Probably no longer made because of the liability issue. If a safety is converted and someone gets hold of the weapon without that knowledge an accident could happen. If they are available I would expect an after market supplier might have them. Try GunParts Corp. or perhaps Brownells. Don't lose that safety lock and spring when installing the safety. If you drop it you'll never find it... I've still got 2 remington ejectors somewhere in the shop, heard them hit at least twice..