Hello, Brian.
My weight during surgery and reversal was right for my height and frame so I don't have the experience you have asked for, but I hope this is helpful in other ways. If you trust your surgeon and he /she is not worried, you should be fine. Start now, two weeks in advance, to cut out sugar. You know that sugar can contribute to j pouch problems, and lead to frequency, bum burn, pouchitis. Cut way back on highly processed foods now. A few weeks after reversal you can try to have vegetables and fruit as long as you peel them and cook them very well so you don't suffer frequency, which will lead to burning perianal skin and painful fissures.
Start now to stock your kitchen and freezer with nutritious, high protein foods so you'll be well prepared when you come home from reversal. Get rid of sugary items and processed foods before you leave for surgery. After reversal you'll have to eat starchy foods like white potatoes or sweet potatoes, sourdough bread, or plain white rice to try and slow down output and these are not overly refined or highly processed. Go slow reintroducing fruits and vegetables. A plastic bidet squeeze bottle will save you from burning perianal skin, or get an attachment bidet for your existing toilet. Make a list of your questions and ask your surgeon about the pressure your weight might put on your pouch when sitting, especially if they had to join your pouch very close to the opening. I truly hope your surgery in two weeks -- and your recovery -- goes well. Take care of your pouch so it will last your lifetime. Best wishes.