I was thinking that to simplify this, one could select the block to scale off of, so it could work on any drawing regardless of the titleblocks name.
yes. exactly.
we draw everything in modelspace, so if the scale factor was not physically visible just yet, I type in LI for LIST to get the block's scale factor.
We always use a 34x22 sized border at 1:1 (SF=1), and scale it up from there. So, basically the limits would be set to 2'-10" x 1'-10" at 1:1. At 1"=1'-0" (SF=12) the limits are 34'-0" x 22'-0".
The routine wouldn't necessarily need to automatically pick the insertion point, just get scale, I'll pick the insertion point, insert at proper scale, then explode.