Don't rule out anything. True, taller, lanky body types don't tolerate G's as well as the short stocky type but it varies too much from person to person. You may have no problems at all pulling Gs so I say go for it. There are plenty of airplanes out there that don't pull a lot of Gs if you discover you can't pull 'em. Good on you for looking way ahead at all the obstacles but dude, pulling Gs is the least of your worries at this stage of the game. Getting to pilot training is hard enough...baby steps. If you can't let it go, then I suggest you go get some rides in something aerobatic that will pull Gs. Then you'll know what you are up against. Good luck.