My 120 plus year old house, with remodeling about 85 years ago has the
same kind of challenges. Although there indeed may be no blocking as
mentioned by an earlier poster, there is just as likely a chance to
find flocking in odd places/spaces/spacing.
When they installed the heating system in the 20"s, they made a square
channel to run some pipes up. If I didn't look carefully I could have
missed this "channel" in a little hallway. In addition, I created my
own "channel" in an upstairs bathrood by putting in an angled wall
behind the toilet (the vend pipe had been boxed in, just on that
floor). This gave me a shot down and up (I'm 3 stories, not sure what
you are dealing with). I rand a plastic onduit up this for future
purposes, and left a pull string in.
I was not able to find a place where I could run a 3 foot drill bit.
Before I got carried away with trying stuff, I would drill a small
pilot hole large enough for a 4 guage ground wire and use that to
determine how far I could go before hitting an obstacle.
IMHO adding the channel in the closet may be your fastest alternative.
You can always consider doing what they had to at I believe it was
Sears tower where they realized they had left out floor to floor
chases, and had to add and external chase! You could probably hide
that along side a chimney.