I have a relatively stocky build and am short for my weight. I find that I have lots of trouble handling opponents who are say, 3 inches taller than me.
Specifically, in a tie up, I find that I am unable to set up and attack properly. For example, my taller opponent can post his head on my shoulder/collar and keep his hips out of shot range. This usually allows me to pummel and sink in an underhook, but because of the height difference, he is able to crank on a strong overhook and again nullify my attack. I am unable to 'jack' the under and put him on the defensive.
Any ideas or principles that I should follow to help with the situation?
I don't have much wrestling experience, but it sounds like an ideal time to snap him and go behind if he's pressuring into your shoulder with his head. Use his momentum and his leaning down against him
I would suggest a duckunder.
I'm a short stocky guy too. Him pressuring down on an overhook has nothing to do with height. I'm betting that the most likely reason in your case that he has an overhook and your underhook isn't worth anything simply comes down to head positioning. If your head is in the right spot - with your cheek almost touching your underhooked hand, and your forehead in his ear/temple, then you've got a nice underhook - and he's got squat.
If he is cranking down on an overhook, it's because he's got dominant head position, not you. Fight your head back inside.
Also, you do not need to "jack" your opponent with an underhook. There are other ways to use an underhook. What I usually do instead of trying to jack a guy up with it, is to pull him towards me, keeping his weight very heavy on the same side foot as I've got the underhook. You keep your hips tight to his, facing into him, inside head position, suck that underhook tight - so your elbow is tight to your own ribcage, and step away (keeping your elbow tight!) from him. This is the opposite of jacking him up, it slows him down, keeps him off-balance. You must keep moving!
If you're striking, go ahead and unload on him. In a wrestling/grappling scenario though, DO NOT just hang out in an underhook. An underhook is a means to an end (takedown), not an end in and of itself. Use your underhook within a second or two (seriously) after getting it. Don't give your opponent any time to re-adjust his positioning.
Regarding other parts of your post...
If your opponent is posting his head on your shoulder, and keeping his hips way back, he is BEGGING to get snapped or shucked.
Also, the idea that his hips/legs are out of shot range isn't really true. No one's legs are ever "in range" unless YOU move your opponent. You need to move him and set him up - put him on his heels, bring him too far forward on his toes, get angles, get angles, get angles - THEN he is in range for a shot, but usually only for a split second.
Leg attacks aren't about "range," they are about motion, angles, misdirection and timing.
Why tie up? Don't try to wrestle 'tall' with him. His long, lanky legs should be right there in front of you. Shoot on them. Use your lack of height to your advantage.
Shelton has a good point - Nothing says you MUST tie-up with him, and as a short guy, I always felt like lanky guys were actually easier to shoot on than guys my own height or shorter.
as a tall lanky guy i have alot of trouble with shorter stockier guys in my division, use it to your advantage your low center makes the shot seem way faster try not to tie up just go for the shot.
(i dont really compete in wrestling, just no gi grappling)
Wow, thanks for the replies. More are welcome of course...That info about looking for angles to attack the legs has really got me thinking. Can't wait for my next training session.