At 6 ft tall and 295 lbs, you're heavy but not so heavy I'd be concerned about putting you on one of my horses and NONE of them are 17 hand and 1700 lbs. I've got a couple stock horses that are over 16 and probably close to 1500 lbs, and I'd put you on one of them in a hot second.
For me, it's about the build of the horse like QtrBel says AND it's about how the rider rides. Are you fairly well balanced, can you ride or post without bouncing around like a rock? With the kind of experience you've had, I'd expect that answer to be a yes, and I wouldn't be real concerned about it. If the horse is in shape, they'll help you get in shape real quick. Since you've not had a horse for 10 years, I'd also be expecting you'd start out fairly slow and shorter duration rides to build up your stamina and muscle memory again. I'd suggest in 6 months of regular riding, you wouldn't be asking that question again.