You cannot reach that ZFW value (in lbs) with the Preflight menu. We made a reasonable assumption of how much a plane is likely to be maximally overloaded based on Jan's career flying it and allowed that value...beyond which we didn't expect anybody to try. If you max out all the passengers and cargo bays to their limits and set the wt factor to 1.5 (to simulate a plane full of 200+ lbs people) then you'll end up with max ZFW just shy of 126,000 lbs. We made assumptions also about "nominal cargo density"...in other words, we assumed folks wouldn't simulate a cargo hold full of lead. Full fuel with max ZFW via the preflight menu that gets you to 161k, 25,500 over MTOW, which we thought should satisfy users wanting to try some overweight flying.....for at least 99.9% of use cases.
Now You CAN achieve that ZFW value through the regular X-Plane weight sliders....BUT....with a caveat. We custom set the weights whenever the preflight menu becomes visible. SO...you can set total payload weight to approximately 70800 lbs (you probably won't be able to achieve 143511 ZFW exactly because of X-plane's slider resolution)....but once done and you "Apply changes", then do NOT open our preflight menu after that...as the total weights will be reset based on where the sliders were last set. This will allow you to simulate your overweight flight....but I suspect you may really have a challenging time with your climb rate and takeoff speeds.
I think a ZFW of 143,000+ lbs....were some official to find out that you actually loaded the 733 that heavy...might have a thing or two to say about that...as well as any license or certifications or job security you might possess
Now if you were to say, "this is annoying, I like to fly 20,000lbs overweight on all of my flights....then we can up the wt multiplier for a future release, I'll admit, you're the first one to ever ask to achieve a weight this heavy to my knowledge.
-tk