In developing a track plan you may wish to consider additional issues. How permanent is this to be? If long term, think of the level of health for you and RR running visitors will need to crawl under a duck under. Around the wall running opens up a whole new drawing board.
Also, what is the purpose of you layout? Is it for display running of the same couple few trains or alternating between a much larger collection of trains?
From your track plan I see a rather nice display railroad with the ability to handle several trains running simultaneously.
Possible problem: with any sizable collection or growing collection without an increase in staging you will have a lot of 0-5-0 shifting going on which only exposes trains to damage.
You mentioned that there is service of the furnace from non layout sides. That hints to a much larger basement area.
If not an around the wall how about a pair of long fingers sticking off along each of the two continuing walls beyond the sketch.
Depending on type of equipment you work with, the fingers could be point to point passenger terminals or one passenger terminal and one freight yard or two freight yards or etc.
Another way to develop a storage area is to build a subway ramp down directly below the overpass ramp up. The subway multi track staging could run a full 360 then rise below the desending overpass ramp.
Photo shows a 0 scale six track staging area built under an industrial / mining site.