Hey Drex,
There are certainly no hard and fast rules on what you can and can't do, but some guidelines on advice for you.
Jigging rods are generally built to handle the absolute extremes of their materials, construction and design. Fishing incredibly heavy drags on very light powerful rods puts alot of strain on all the components in your tackle.
Rods are generally ( or should be ) built with either in a spin or conventional/overhead design after finding the spine of the rod blank, and bulding according to which way the rod is going to bend whilst fighting a fish, and placing the guides accordingly.
On a spinning rod, the guides will be on the oppposite side on the blank to what they will be on a conventional set up.
So if one were to use an overhead reel on a spinning rod, you would in fact be bending the blank the "wrong way" if I can use that term.... It can work fine, but can also place ALOT of strain on the blank and in a worst case scenario cause breakage in a case that it never would have if the rod was being fished with a spinning reel, or using a dedicated overhead rod.
If you fish slightly more conservatively, and don't put huge pressure on the fish, you shouldn't have any problems, but they could happen.
Another aspect to consider is that guide placement and such are put together on each spinning and conventional version to help them work how they should, and differ alot between the two rods.
The experience of using the "wrong" reel or rod, will greatly reduce your jigging experience.
As I said, it certainly can be done, but in my opinion if you are heavy jigging, for mean nasty fish, I'd get a dedictated oevrhead jigging rod to go with your overhead reel.
Cheers
Nepps