I have a fairly early Model 586 no dash with the M modification stamp.

While I have no scientific proof, my impression and opinion is that the early L frames were built on all new equipment and as S&W was still trying to capture a police market that was rapidly switching to autoloaders, they wanted those models (the 586 & 686) to really show what S&W was capable of. Mine is beautifully fitted and polished with an excellent trigger pull and was the first gun since a Dan Wesson Model 15-2 that I owned that just seemed to put bullets right where I was looking without hardly trying.

I think if I were in the OP's shoes I would look for a high condition, hardly used 586 no dash or dash 1. I think he would be quite pleased.

The key word in your reply is CHARACTER and I agree wholeheartedly. Pick up any of my 5 screw guns, then handle the few newer guns without pins, recesses etc. I own. World of difference.
MTCW