Spanner in the works time.
I am also a little past 50
and took up road riding about six or seven months ago, after being an mtb only rider on and off since the late 1980's.
I am 6'1" with a 34" inside leg and taking advice from my roadie fanatic son (who is the same height and build as me, just slimmer and fitter
) I chose a 56cm / 22" frame, set up with a 110mm stem. I recently finished a second road bike, which is built to very similar dimensions. Both these bikes ride really well and fit me perfectly, although common convention would say they were much too small.
The best thing to do is visit a bike shop where they are able to give you a good idea of fit, as my personal opinion is that reach is probably more important than frame height when it comes to comfort from back, neck, shoulders and wrists.
"Try not to punch any clowns"