How's progress? I was enthralled with your photo-doc stripping the deck for a fuel tank install. Pretty bold ! How's that going? It's tough fitting all the fuel tank you'd like into this boat. I installed a 40 gal. tank under the console and forward making a seat ahead of the console.
I used my SR6 extensively with the ballast enabled for diving and have to agree it makes for a much more stable boat when sitting/anchored. The boat just settles into the water and does not bob or rock. The original intent was for rescue operations to get very close to the water to pull people onboard easily. But we aren't doing rescue.
Still, we opted to plug it up. I found that in rough water we'd constantly have water splashing up over the back transom and we'd come up from a dive to see the deck full of water... Plugging it raises the boat and keeps it there. But, with more rocking.
In retrospect - had I known - while we had the boat in pieces I'd have raised the back transom straight across. And installed long shaft. And kept the ballast enabled.
As for the rest of the discussion, I think getting as much weight forward of the centerline is best for this boat. Especially if you can afford plenty of power.
We have made double-duty use of the original arch, filling it with mesh netting to store and contain life preservers and etc.
We are seriously considering a transom extension now to make more room in the back.