As a serious drinker of Abbot in the 1970's I would like to second Dennisking's words.
There is no comparison with today's lower gravity offering. If I remember rightly, it was closer to 6.5% and a very much sweeter, thicker, malty beer. Indeed, it got quite sickly after 5 or 6.
I made several beers from DL's book, and they were recognisably close. I suggest that his recipe would be closer to the Abbot of old and again second Dennis' opinion that the yeast would be very important. If using dry, Windsor would be my first choice, otherwise WLP002 or Wyeast 1968. Worthington might go a bit too dry, but would be worth a go.
If you are going to adjust the water, drop some of the Gypsum in favour of Calcium Chloride.
Having said all that, you like the current Abbot, so you would probably hate the above! :sick:
So try DL's recipe, but go for say 5% and use Nottingham or WLP006/7/13/23.