That Ruger sounds like a nice package indeed, congrats on the price too.
You won't find many BSA fans around here, nor am I one at that. With that said, I do own 2 on a couple barrels.
If do you go with a BSA, I highly recomend going with the "higher end" (if one can say that about BSA) lines, like the Panther, CatsEye, or Platinum lines. These have the better glass and better multi-coatings on them, not to mention a little less reputation of breaking than their lesser models. As of the past couple years evidently they have rehauled the factory, production, and QC of their scopes and are a far cry from the POS they use to put out originally.
A 4-16 would be a fine power and is around my favorite range of power for a varmint rig. Thats what I got on my 243 Handi as of right now.
If you got a little more to spend than $100 there are a lot of good choices out there for not much more. Like a Mueller, Millet Buck Gold, or Bushnell Legend 5-15 Mil-Dot. All under $200.
-Aaron