Thank you for your help,
80 gram shafts come in a variety of flexes (R, S, X). An X-flex might be more common because most golfers that use a heavier shaft will tend to have a higher swing speed.
You see 80g wood shafts in S and X flex on a lot of OEM sites. Some OEMs allow you to purchase a custom shaft for an up charge - some OEMs like Adams use real aftermarket shafts in their woods. You've got to do your research. I'd avoid Taylormade's heavier shafts - they are typically not the real deal shafts and have a reputation for putting crap shafts in their clubs. On the other hand, Titleist has shafts that are made to their specs but are typically of very good quality.