If I am understanding you correctly what you are saying is:
1: My back swing is too flat.
Your Backstroke is Aroundish.
I am on the elbow plane going back
Kind of, but that's irrelevant.
and my over the top move is an attempt to get up to the TSP.
No. Your over the top move is caused by your hips and shoulder alignment.
2: I need to focus on getting my shoulders to move vertically in both directions.
No. You need to stop going aroundish and use the Plane Line.
3: I'm too flat with the shoulders going back. Yes.
4: I'm over the top because I'm attempting to not be too flat going forwards.
You're over the Top because your shoulders and hips are aligned that way.
All that I'm asking you to do is to get into your address position without a club. Then, move your right foot back (away from the target line) a few inches or more. This will move your right hip out of the way so that your shoulders can turn without going around. Your spine will not move or sway or tilt. Your head should remain stationary. Lastly, move your hands to your right and up. Try to trace the Plane line.
This will re-align your shoulders and Hips and you will no longer come over the top.
I started out as a swinger but I am not built for it.
I'm 6'5 285 and very muscular and not exactly the most flexible person in the world. I failed all but one portion of the TPI Flexibility test.
I have gotten a lot more flexible but I don't think swinging is in the cards for me.
I have all the time in the world (job not doing shit right now) so I can literally practice for 8 hours per day if necessary.
I just need to start getting these things squared away.
Not to take this off track, because Daryl is doing a terrific job.
I don't see too many reasons why you couldn't stick with swinging. You're photo shows classic swinging alignments. Flexibility and muscle has little to do with it. It boils down to what your natural tendencies are.
I don't see that you have any issues in being overly muscular and while flexibility can be a nuisance, it doesn't determine whether one should hit or swing.
I'm a masters level powerlifter and plan on challenging the National record for my age/weight group this year. I speak from experience in that muscles and flexibility do not determine hitting vs. swinging. Homer said, "if strong hit and if quick swing" but those are generalities. Homer was a genius at observation. All that really matters is what happens between release and follow through and to be more specific, impact.
Controlling the right shoulder (zone 1 and 2) is vital to both procedures. Learning to hit can help your swinging because it forces you to trace a radical inside/out path and trains the pivot to move along an cross line delivery path (2-J-3-B). It's very difficult to perform this and roundhouse.
I'm done - coach Daryl is providing some great info. I just want to make it clear that hitting and swinging tend to boil down to whats in your DNA. It's great to be able to do both, but you'll always have a tendency one way or the other.
__________________
Bagger
1-H "Because of questions of all kinds, reams of additional detail must be made available - but separately, and probably endlessly." Homer Kelly
3: I'm too flat with the shoulders going back. Yes.
4: I'm over the top because I'm attempting to not be too flat going forwards.
You're over the Top because your shoulders and hips are aligned that way.
I see a detail that separates you from the great ball strikers at the top. And I think it is important.
You are flat with your forward bend from the hip. And perhaps too flat. So steeper is probably better. But I see something else that I think is even more important.
Your shoulders are steeper at the top than they should be with the given spine angle - on both pictures. At the top, seen down the line, the shoulders should probably be flatter than 90 degree to the overall forward tilt. Take a look at Ben Hogan for instance. Yours are clearly steeper than his (relative to the overall forward bend from the hips).
I believe you are steepening your shoulder turn by bending your spine sideways.
If you stand straight and only do this "spine bending part" of your back swing, this steepening will manifest itself as a side bend in your spine that bends your head and shoulders towards the target. Things may look and feel different at the top, but nevertheless you are setting yourself up to lead the down stroke sequence with your upper body. There will also be a disconnection between this upper part and the rest of your body.
To produce a good, on-plane down stroke you need to produce a side bend in the opposite direction of what you're doing now. One that drops the right shoulder towards right hip, while the hips move forward during transition. The left side of your upper body should become stretched, and the right side compressed. This should happen during transition and kept through the ball. I think you need to eliminate your "reverse" side bend at the top to get there.