Anyone know who to get ahoold of for historical site permission
Some historical sites are private, you can get permission from the owner or the group or organization that owns them. If state owned? You might not be allowed. I believe federal historical sites are a for sure NO.
So, it depends on who owns it. County,state,private..........One thing I've found is to start at the place where you want to hunt and ask there first(if occupied or maintained by someone), they will point you in the right direction most of the time.
Get to know your local Historical Society if you have one! It might pay off!
You also might be in an area where people could care less if they see you detecting. That does play into it too. Not to give bad advice but it is true.
I detected schools and a lot of other areas of Ohio and never had any major problems. I was told to put it away at one state park and waved at in another. Just be civil and nice to who ever confronts you and don't dig "holes". I got real good at popping targets out with a screwdriver or something similar.
GiB has a great idea too! It seems when people see you "digging" they freak! If they see you poking the ground with a small screwdriver they are curious.

Plus in some areas surface finds are allowed and if you have to "dig" they are not. So your wording is important too. Holes and a mess will get you kicked out of areas that are allowed!
Use your common sense and judgement too. Even if it's allowed, it's really taken care of, or there are a lot of people around sometimes it's best just to move on.It avoids headaches... Just my 2 cents...

Area means a lot.