I have a berkley cherrywood 6'6" medium light  I was wondering would this be adequate for a dropshot set up. I see where alot of people in videos use from 6'10" to 7'3" medium light. I was wondering would my rod be long enough or have enough backbone for a good size fish.

Length of rod is preference. I can't answer you about the backbone of that rod but take in consideration that you're finesse fishing with ligher gear. You're not horsing fish around while finesse dropshotting. Your rod and reel do all the work and you want to make sure you have a smooth drag or you can back reel. If you plan to be in thicker cover with heavier line (bubba rigging) then you'll want a medium action rod.

Use what you have. If it doesn't work for you look into upgrading equipment.

thats true Im not looking to horse them the taper is  moderate. It will give them time to load up. I should be alright  I fish for Spotted bass with the occasional lmb in the mix at the lake so we will see how it works out.

I've been looking into these as well, and while 7'2", M XF seems to be what Shimano recommends, I don't see why yours wouldn't be suitable.   Its one of the few setups I haven't tried much of yet, and definitely seems to be one to have a dedicated setup for.