I understand where Godric is coming from. Lifting can be as much a mental pursuit as a physical one. And changing a successful program, even slightly, can give a fresher approach to workouts. All the compound exercises in his 5X5 scheme are tops for strength. Though a lot of guy's do not always gain much in the way of increased muscle mass following all this.
Might try shifting to a more set/rep type of program for muscle size. Old saying in BB'ing (from the glory day's of Muscle Beach...I had been told), "More blood, more muscle". In other words, encourage the pump more. Which does not mean that you have to use wimp weight for pump outs only. All this while keeping those core movements you are doing now. Something like 6X7-10, 8X8's, etc. Even 10X10's (GVT), one of my favorite change of pace workouts. Experiment with these and others. As a general rule, 90 seconds between sets. Or 120 seconds max for BB'ing style training.
With the PR you have, you may have hit the mother load as far as strength and size go. Exceptional equipment, probably best (for me anyway) when using partial rep training with it. Little too long (even for me)to explain here, so might want to do a search on that style of training.
Keeping the original A & B plan alive, I would tweak the B workout a bit. Keeping the A plan intact. Something like:
1)Hack BB squats. Think of it akin to a reverse DL, but hitting the legs much better. (one of my favorite leg movements)
2)Shoulder press. May alternate it a bit by doing sitting presses. Consider push/jerk presses from time to time.
3)Upright rows, remembering to keep the bar close to the body at all times. Guy's who run into trouble with this movement tend to lift the bar too far out and away from the body. Inviting undo stress on the shoulder joints. If uprights not your thing, than Hi-pulls by all means.
As far a diet goes; lower carbs and high quality calories. No big secret about gaining pure muscle mass over just getting fat. Good Luck.
