The fixed-sighted Service Six was not available in the 6" length, so an adjustable-sighted Security Six would be the closest option, unless one were willing to compromise one's standing among certain of their peers and buy a vintage Charter Arms. Charter Arms made a 6" 357 with fixed sights. I wouldn't mind having one of those, though it would definitely be a woods/range gun only. It was obviously voted out of production by folks voting "no" by withholding their dollars.
I most recently had another 4" Service Six, but wanted a 3". I did the logical thing and sold it, but had it not already been a tad too heavy for my liking, I don't think lopping off an inch and repositioning the front sight would have been all that illogical.
I want what I want. I spent many years wanting what everyone else wanted and was never quite satisfied with any of it. Now, my aim is to have what I really want and chop, swap or modify as necessary to achieve that. It might take more effort or cost more money, and might not be what someone else wants, but if it's truly what I want, I won't be fretting about "resale" value or who wants it when I'm gone.
One bug in that ointment is that blasted Colt, King Cobra, which REALLY pushes a lot of the right buttons, but I'm not falling for that again, especially for $900 only to find out I'd have to change something.