That R90 is nice. The old bikes just look right. My mid-80's Peugot still hangs in the garage, ready to go - it's just not comfortable to ride for more than ~10 miles anymore.
In case if gives you some ideas, here's a link to my foray into a gravel-like bike (older cyclocross frame with some newer components):
http://forums.pelicanparts.com/off-topic-discussions/720544-ultimate-bike-thread-214.html#post11262591
Not quite full gravel; am running 700c x 35 tires which is cushy on bad roads. I tend to find taller frames with longer top tubes to be comfortable for longer rides.
Have you considered looking at recumbent bikes? They are usually reasonably-attainable used and it's super-comfy to start a trip with your lounge chair already deployed:
http://forums.pelicanparts.com/off-topic-discussions/720544-ultimate-bike-thread-211.html#post11075869