Reggy,
Weren't you going to buy a Penn International Torque star drag? Or haven't you decided yet? If you did buy one, how do you like it? The TRQ200 can fish 14kg of drag, apparently, which is enough for most fish, in my opinion.
As I've already said a few times on Ausfish, I was using 13-14kg of drag on a Trinidad 40N, on a 21kg kingie in NZ a few years ago, and the fish never took more than 1-2 metres of the 80lb braid I was using, in one "run". The fish was hooked at approx. 80m depth, in over 100m of water, so the reduced diameter of the spool probably meant that the actual drag pressure was a kilo or two higher, at hookup. The kingie was hooked on a jig, so the hooks were through the bony outer part of its mouth - it was not like it was gut-hooked or gill-hooked, and the fish was in prime condition.
The question of whether to use a spinning reel or an overhead for jigging is, like others have said, a matter of personal preference, but it can be hard to know which you prefer until you actually hook up to a really big fish, using heavy drag. I have a Stella 5000SW, which is small but it can fish 13kg of drag (apparently - I've never gone that high), and I've caught some big fish with it, but I think I prefer overheads for jigging. The way you hold a rod with a spinning reel on it, and the way you hold an overhead rod, is different - for me, at least, a spinning outfit puts much more strain on my wrist and hand under heavy drag settings.
As far as the actual jigging itself goes, I personally find it easier to jig with an overhead, but probably only because I jig with my rod butt in my gimbal belt.
It might be a good idea to borrow someone else's heavy duty spinning reel, if you can, before you decide to spend money on one specifically for jigging.
Brent.