Thank you everyone for the replies, I will definetly at least try. I was honestly a little discouraged to even give it a shot. I never thought much about the weight issue until the whole fiasco with flight of passage at animal kingdom and began looking into the other parks we would be visiting. I have 2 weeks! And I'll be pushing myself to progress further and further until it's time to go!
I gave some vague encouragement above, but I'll swallow my pride in order to give you (and others reading this) some more specific anecdotal advice. Based on my experience, you are indeed right there on the edge. I'm 6'1 and similar weight/measurements. Weight is difficult to base the prediction, since scales vary a lot (I always weigh about 10 lbs more at my doctor's office than at home). My current chest is about the same as you, and my belly is a couple inches less.
BTW, I'm hoping I still fit in a few weeks when we go to USO. So I understand your anxiety about the whole thing.
Anyway, I am usually able to fit on both rides, but I have been disallowed even on the same day where I was able to ride (Forbidden Journey). I strongly recommend you spend a few minutes in the test seat trying to figure out the best way to sit and how to pull the harnesses.
If you get a yellow light on the FJ test seats, then you still have a good chance of getting to ride in the outside (modified) seats. It's a bit of a puzzle figuring out how to sit and be able to pull down the harness. Broad shoulders/chest and the belly can both be problematic. Try to figure it out to get a yellow on the test seats. You might get pulled aside in the queue to try the mid-castle test seat, but don't let that bother you. Sometimes on the real seats a Cast Member will give you that last little push on the harness to click to green. Not guaranteed they will, but they might. Of course, even if they do, if you are uncomfortable, ask to be let out to wait in the child swap room.
On Escape from Gringott's, the problem area is shins/thighs. Be sure to empty pockets into the locker before you get in the line. My cell phone and wallet in my cargo shorts almost cost me a ride on Gringott's at HHN last year.
As I, and others, said earlier, for FJ: ask for an outside seat (they have a little more room for chest and belly) and for EfG: ask for last row (it has a little more room for legs).
Reiterating here: Wear loose clothes and empty all pockets into a locker, try the test seats (if you get a yellow light, still go through the line and try), and if you don't make it on the ride, try again later, because it's easy to gain/lose bloat on-site.
I still think you have a good shot to ride both rides, but it will be close (based on my experience with similar attributes). I honestly wish you the best and hope you get to ride both, but if it doesn't work out, don't let that ruin your vacation. There are plenty of rides you will get to enjoy either way!
Unsolicited advice: ask for last row on The Mummy (same reason as Gringott's, but it's easier to fit on Mummy), ask for a modified seat on Hulk, and if you ride Flight of Hippogryph (or Woody Woodpecker) family coaster try crossing your legs to get the lap bar to close. There is absolutely no embarrassment asking for modified seats where available. The only person that will know is the Cast Member you ask.
Finally, relax, have fun, and enjoy everything you can at USO. There's plenty to enjoy, not just those two rides!
