This is Another one of the company's selling Indian muskets, this one would not be correct for 1775. If you are going to buy an Indian musket here in the states I would recommend Middlesex Village Trading Company if for no other reason than they come with the touch hole already drilled. I have one of their Long Land Bess's, way more correct for 1775 than the later period Bess's like the one in your link.
http://www.middlesexvillagetrading.com/M1BB.shtml
I am told that guys doing what you will do with it will need to rework some things to make it look more correct, I just shoot mine on the range and it has been no trouble at all for that.
There are other choices out there, some of them are listed in this thread, but most, if not all of them will cost you more.
Brand new to BP? Make sure you do some reading here on the forum, and try to find someone near you who can walk you through the loading and firing of flint muskets. For starters you will need real Black powder, you can't operate a flintlock on the substitute powders like 777 or Pyrodex. Some folks use FFG for the main charge, I use FG only because GOEX recommended it for a .75 caliber bore, they both work. FFFG for priming your pan only, never use such a fine powder for the main charge. Bullets, these big .735 balls are expensive when you buy them ready made. Casting your own is recommended, and fun, Lyman makes a nice mold that so far has cast me 1156 musket balls. You must use a thin patch with this ball in the Indian muskets, and probably the other makes as well. If you have never shot BP before then you will have to learn to clean up the mess it can leave, it's done with soap and boiling water, BP leaves fouling in a bore like nothing you have seen in a modern cartridge rifle, and because there is salt in it you must clean it up ASAP. You must learn to set your flints properly in the cock, and to keep them sharp. You will also need other things like a powder measure, black powder is measured by volume not weight like smokeless is. A vent pick to push fouling that might plug the touch hole, and a good flint knapping hammer as well as a powder horn. I recommend a proper spring vice so you can strip down your lock. I am sure I left something out but Track of the Wolf, or Dixie Gun Works can sell you it all.
You are lucky, you are starting out with a tool like the internet, any questions you have there is probably somebody here who can answer it. When I started out before the internet I had a flint musket, a can of pyrodex ( all that was to be had around here at the time) and that's pretty much it, I had to learn by experimentation. First thing I learned was to use leather to hold the flint in the cock, second was that pyrodex sucks in a flint lock, third was that it's very difficult to learn to aim when there are no sights on the barrel.
I can't stress this enough, as you are brand new to this try to find someone local to you who can walk you through it, and help you select a musket. There were French, Spanish , as well as captured English, and German muskets being used by the Continental army not to mention the muskets made in the colony's. Try your local gun clubs, gun stores, or search the net for local reenactor groups that might be near you. I know a lot of shooters out your way but they are all into modern rifles.
I almost forgot, these kinds of weapons can be very addictive, I started out with just the one, now I have dozens and shoot them constantly, I have to bulk order my powder on line in 30 pound lots and if I wasn't in the scrap business I would go broke buying lead.