I would definately replace it. If it has no scope mount I believe it will have a flat rear partion of the reciever top which requires the correct mount. They are available. With the "E" prefix it is definately an older rifle, probably 1990's era. You make it sound like a new rifle with the cosmoline and packing stuff on it. I dought it is. I believe you will have to redo the headspace if you get a new bolt head but maybe not with the new baffle. Yes on the bolt head due to the manufacturing tolerances in that part. Replacing the baffle is not difficult but to headspace you have to loosen the barrel nut back out the barrel and use a headspace gage. How to's are available in the FAQ section. You will need a nut wrench and a vice with wood blocks to grip the barrel. Screw the barrel into the headspace gage which you put in the bolt like a normal catridge then tighten the nut. If you have any other questions ask. Someone here will have the answers.

El Lobo