Yeah I'd look for a QH - but not just any one. Do look for a larger one, and look for conformation, what is weight bearing, short back, thick cannons? Is that right or did I just pull that out of nowhere? Anyway someone can surely tell you. Don't just get one that seems good without evaluating its suitability.
When you try it out see how it goes. And don't get one that's really unfit, sitting out in the paddock because it will be a lot harder on it. Get one that is already in work.
Also - think tack. A western saddle weighs a lot which adds to the overall weight. Also check that their back is long enough to cope. As a larger rider you'll likely need a larger saddle which will be longer and maybe not fit some horses.
I'm not a small rider. My saddle is a fairly big size and it *just* fits my mare (its almost too long). I had to turn down other saddles that were cut too long. Saddle fit is always important but I think it is especially more so for the larger rider as more weight improperly distributed causes more harm.