Daniel,
One approach would be to have a bow that you can reasonably comfortably pull to say 28 inches, and use this to work your draw back and draw weight up with lots of shooting. At the same time you can have a heavy bow that you can just draw to say 28 inches with difficulty. Use this to develop strength, pulling maybe 10 times every morning and every evening, until you can pull it failry confortably to 28 inches. Now start shooting with this, and work back draw length and weight. go back to the lighter bow to re-estblish good form and accuracy, switch back to the heavy bow.
You could quite easily end up having three bows, all of which get use, heavy to develop strength, lighter for form.
I think it is good to shoot the heavy bow at distances and with a very different "in-the-bow" style. there is a risk of injury if you try to use the static arm strength draw with a heavy bow.
I can shoot a 90lb or so long warbow at a roving shoot, but maybe half that weight primitive bow for field archery.
Maybe you could pull more that 80lbs. Only one way to find out, make one!
Mark in England