Weight of rider vs size of horse

[JUDYK89@aol.com]

Okay, we've talked about height of rider, and how it doesn't seem to make a difference with the size of the horse, as long as the rider feels comfortable.  And I've just read Susan G's Tevis study results. But I'm pretty nervous.  I'm a heavy middleweight, (please don't make me say how much on a national forum) and I'm buying a 14.2 gelding.  I'm told he's very strong, very well balanced and he has 2-50's under his belt, but with a lighter rider.  Where do I start?  How slow should I start him with my weight?  I know it will depend on the horse, but I'm so nervous because I've had some major lameness issues with my other horse and that's why I'm buying a new one.  I'm excited and scared at the same time.  Will be seeing him and trying him out next week.  What should I ask the seller, what should I look for on the horse, and on his back?
Thanks,
Judy