What I use to do with these old reels was to open the side plate and spray in WD-40 quite liberally. Then I let it set for a couple of hours. Next I used the hot water facet in the deep sink in the basement and flush out all the old grease. When that was done (and thoroughly dry inside - sometimes I'd use my wife's hair dryer), I use standard reel grease (lightly) on the gear teeth and reel oil on the bearings and shafts. Kept my 300 & 308 going well for many decades this way, so I know it works.
Also, due to the fact that it is difficult to manually close the bail by hand, get a 1/2 doz. bail springs (online) and keep them handy. You can manually close the bail by sliding the bail stop out of it's slot, but it's inconvenient. Best to just close the bail with the reel handle and replace broken springs when you get home. This is why I always use to carry a spare reel.
"A voyage in search of knowledge need never abandon the spirit of adventure."