Spenda, Welcome to the fred. Impressed with your pb's btw.
My take on your build-up would be to do 6 weeks hadd 70% (building to 50mpw), 6 weeks incl 2x80% runs, then for the last 6 weeks moving to a more traditional schedule but with hills included.
By traditional I mean P&D or Hal Higdon based, with your own tweaks to make it bearable.
I think you could Hadd all the way to the marathon, adding some faster stuff (as Joe did), but it
depends on what "floats yer boat". Good luck with the comeback. No reason why you can't pb again btw, my pb's came at 48 years young, and now I'm 50 I still believe I can pb at marathon.
Sneglen, Hadd (and the others on here) all quote % of max.
Funny Hat, Good luck with HM. Look forward to your stats.
Laureate, E lo stesso per voi!