Jpouch suitability?

Not having Crohn's of the small bowel.
Not having Crohn's anywhere.

That's about it.

I think all of the things mentioned above are considerations:

Weight
Inflammation in the small intestine
Age
Past steroid use (this would usually only slow things down - not make you a worse candidate)
Prone to scar tissue
Having a history of Fistula (because this points to possible Crohn's disease)

I think it's best to consult a surgeon to ask these questions. They would be able to tell you very quickly if you were a candidate. I would imagine there is a 99% chance you are.

For whatever it's worth, I cried when I googled images of stomas for the first time - I couldn't imagine having something that hideous. I had an ileostomy for 2 and a half years and by the end of that time, I couldn't have given a carrot what the stoma looked like - it was just another body part that I didn't love or hate, but was neutral about. I had the reversal because it became available to me and I didn't like being so dependent on specialist supplies, having to store them, etc. The actual wearing of the bag, and the changing of it, was trivial by that point. Most people who have j-pouches don't spend enough time with a stoma to make this adjustment. I bet if they had to wait 2 years far more people would choose to stay with the stoma and elect not to have a j-pouch.

If I knew what I know now, I would have stayed with the stoma. I was taking a gamble on the Crohn's not returning quickly - it returned quickly. It's mild inflammation for now, but the symptoms are still an absolute pain up the arse (and Entocort seems to be stopping working).

It's my belief that there are many people with j-pouches putting up with nonsense symptoms like mine, but downplaying or minimising them for various reasons. Not everybody of course. Some people do have excellent outcomes, but what does that matter if you have a subpar outcome? Likewise, if you personally have an excellent outcome, my subpar outcome will mean nothing to you.

People seem to think they need to hear "success stories" or whatever to make the decision to have surgery. They don't. They're just not quite ready to make the leap, but when they are, the internet literally won't even figure into it - like it didn't for me or anyone else who makes that irreversible decision.

I cant comment on all the many, happy people with jpouches, since i opted never to pursue one after step 1'of a step 3 jpouch, and kept a permanent ileo instead. I will say that in my own, personal experience, the end ileo has given me back a life roughly equivalent to life pre UC... I mean, no substantive quality of life reduction for me whatsoever vs life pre UC. No one who I dont want to know about my ileo has a clue that I have one, and it does not interfere with my full resumption of recreational and athletic activities (eg tennis, cycling, hiking, travelling a lot) that I enjoy that were severely curtailed or risky in most of my UC years.

Would I rather have never had UC at all? You bet. But an end ileo is something one can "try out" in a 3 step pouch procedure, and I was never grossed out by the thought of it. The idea of my cr*p reservoir being artificial and disposable appealed greatly to my gut instincts (pun intended) as opposed to being made of tissue that would be part of a body with a track record of attacking its own tissue when exposed to waste bacteria. Also, I had internal hemmies and so I suspect i'd have felt above normal urgency holding in anything in any jpouch, just based on my experience when pressure built, but who knows. After years of being a problematic patient/non responder for Uc therapies, I was pleasantly surprised how seamless life now is with an end ileo. Just my anecdotal experience, of course. If the end ileo had turned out to be a problem for me, I probably would have proceeded onwards but it was a done deal for me with how good life became once I got over the post surgical recovery (even right after surgery, the absence of colon pain was breathtaking)... and wow, did Uc ever rob me of too many years-- I just wish I had done it 10 years earlier but I completely understand the fears-- it's why I delayed so long. whatever surgery one pursues, seek experienced and communicative surgeons who will answer all you questions.
Best wishes and good luck.