Hi,
I am responding to your question mostly because I am very interested in the 66 for myself as a carry weapon. I have been carrying concealed daily for the better part of 20 years. Usually a Glock 19, but sometimes a 1911 or Browning Hi Power.
OWB is much more comfortable that IWB. In terms of IWB, something that has a flat or smooth back will be less likely to pinch or irritate your skin (ex: Cross Breed or Alien Gear).
It really depends on your build. I am short, 5'7" and about 160. I find it pretty uncomfortable to carry in general. I find that taller people are much more comfortable carrying in different manners, especially IWB.
dress is important too. My job allows me to wear casual clothes, so having an untucked shirt is pretty standard for me. Also, being North of you, I can wear heavier clothes for more of the year, which helps.
A good quality OWB leather holster, such as Galco or Safariland should suffice. Your belt will probably be more important than any good holster. I typically wear a 1.5" Wilderness Tactical instructors belt. Beltman makes nice affordable leather belts. Stiffer is better in my experience.
Kydex is another great option. Great retention, stays put and feels secure. It's also not as affected by environmental issues. 3-5 o'clock belt positions are standard and hide well, as does small of the back. Shoulder holster are good for driving but pretty much suck otherwise.
Probably not much help. If you elaborate a little on your body type and normal dress pattern it can be narrowed down a bit. Most importantly, post pics of your 66. I really would love to get one. After all these years I've never owned a revolver. But for some reason, I feel that I need one.
Regards