Your Ruger MK II 22/25 will do just fine to get you started. If it has adjustable sights, so much the better. You don't need a European ISSF sport pistol to shoot NRA Conventional Pistol. But if you can afford one and it's what you want, have at it! My dream pistol is a Hammerli 280 or the new SP 20. By the way, I wouldn't touch a IZH35M with a 10' pole unless it had been totally worked over by someone who really knew the trade. I had one and even after sending it back to EAA for repairs and adjustment it was the most unreliable POS I've ever owned. Some choices you might consider in either the new or used market are:
S&W Model 41
Browning Medalist or Nomad(used only)
Browning Buckmark
High Standard any Mod 107 original or military frame (do not buy a stainless steel Mitchell knock-off!)
Clark Custom or Volquartsen custom guns of any model.
A resource you can read at your leisure is
www.bullseyepistol.com You'll find many tips for the new shooter and advise on selecting equipment