Ok, I'm not Wes, but I'll give you a bit of insight. Two years ago, I was 5'9" and weighed 260, and wore 38 inch waist jeans. Riding ANYTHING besides MF, TTD or Wicked Twister was no problem. Going up to the station on MF was always very unnerving- not about the ride, but about whether or not I would be able to ride. I was never denied, but I was also always close.
In those days, it "wasn't safe" to ride MF unless you could fasten the seat belt and pull 1" of slack on the belt.
Last weekend, they were stating the rule as "You must fasten your own belt, and then pull 1/2" of slack on the belt. Why 1/2" was unsafe two years ago, and now is- who knows?
Also, I saw ride operators behaving differently from one another. I saw some that were helping people, and others who would not help.
And, it has been stated before, but is worth stating again- it's not so much your weight, but how you carry it. I saw a 125 pund woman have trouble fastening her own belt. Pulling enough slack was no problem, but she just couldn't see the belt latch, and had touble fastening it.
On rides with OTSR's, it's going to depend on the ride. Arrow OTSR's seem to be pretty accomodating to larger riders, but Intamin's are pretty snug. B&M's are somewhere in between. Also, some B&M's have special seats on the train that are a bit roomier for larger riders. It might be a good idea to do a bit of research about the rides at the park you are going to.
It would be real nice if you could find some coasters that were friendly to your size now, so you could get at least a taste of what you're heading for.