What is the maximum results I could hope for?

[wrknonit]

Read the stickies in the training forum and learn what progressive resistance is and how it works. Focus on getting stronger and EAT! At 6'7", 180lb would be anorexic!

 

[poysyn]

Well I have been dieting pretty hardcore, restricting calories and drinking tons of protein shakes...

I'm guessing a lot of this is simply not having as much food running through my intestines...but I'm sitting at 199lbs 42" and 39.5" waist. Why are my muscles shrinking so fast? I didn't have much...but I wanted to keep what I had

This is definitely the problem. If by hardcore you mean under 2300 calories than that is a straight up mistake. Increase calories gradually until you start to see gains. If you eat clean (and not TOO excessively) you will see gains. There is no reason someone your size should be stuck at a 150lb bench with even a decent diet..let alone a good one.

Post up what you eat in a day and how many calories your consuming