Sweet. Look for IDPA, USPSA or ICORE matches in your area. IDPA has a 4" barrel limit (4.2" actually), so your M65 would be your IDPA gun.
As far as equipment, if you've a holster, speedloaders & holders, go shoot a local match with it. If you decide you want to stick with it, get a kydex holster & speedloader holders, and some CompIII or JetLoader speedloaders. ICORE and USPSA stages tend to be longer, requiring more speedloaders & ammo to shoot, so gear-wise, IDPA is the easiest to get into.
Finally, depending on where you live, there may be other action matches available. One local venue hosts a monthly "fun" match - IDPA scoring, but shot "freestyle" (i.e. run what'cha brung and no rules about cover, concealment, etc). We also have ZSA
matches around here - also freestyle and run what'cha brung. Challenging & lots of fun.