this is an interesting project,, cause you are in a grey area,, where results are difficult to predict,,,,that being said, I sinewed alot of bows just to see what it would do and learn about the process,, that is enough in itself I thihk,,
I am out on a limb spitballing, but I think you will gain at leat 20# draw weight, and that will add about 20 fps at the increase draw,,I dont think the bow gonna shoot much harder at 10ggp than it is now, but it could,,depending on retained reflex,,
I dont think much tiller will be needed,, let the bow stabalize before scraping wood as the sinew will take a while to stretch,, I would leave it braced hours at a time for a few days,, before taking off any wood,,
dont worry aboug making it shorter, if you get it shooting nice, and want to shorten it later you can,, with the sinew on there you could go easy to 60 inches,,
good luck on your project,, keep detailed notes on your procedure so you know what you want to do the same and differently on your next one,,,,