Thanks Guys,
Appreciate the input.  Keep feedback/idea's coming.  This is a one time, chance of a lifetime.  
Want to get it right.
Funny.  That is the first thing that 
Derek at Miracles said.  24" depth.  I said I could squeeze 20" from current 
18" that I have with 65Gal Tank.
I've been thinking about that.  Bit of a challenge since I have the Kitchen Tank Sump right there squeezing me for space.
Then last night I realized with 
Wider Tank 48" the stand would spread out so not an issue.  K-Sump would slip a bit under the other tank stand. 
Ed, I was also thinking like you that a shallower tank would get me more lighting penetration, and I could stop standing on stool to reach in.  20" sounds wonderful for maintenance!!
My hole in wall is fixed.  But I can reduce it easily with drywall.
I don't want to rip apart walls too much, but anything is possible once old tank is out.
This picture of my sump-room framing taken 15 years ago explains things.
My main priority right now  is to plan for Current 65 Gallon move out.
That way I can open up Sump-Room for some ruined drywall replacement, and built stand etc for new tank.
Once I have tank out, I'll start the new thread in SPS section and maybe others can help too with ideas.