I've used Savage lever-action rifles for quite a few years. I absolutely LOVE them.
I don't have my book upstairs, but I think the 99E was pretty much the same as the 99EG, but the take-down version.
A couple of things that you need to be aware of with the takedowns...
The threads have a tendency to get looser and looser the more the gun is disassembled and reassembled.
Unlike takedowns by Winchester, there's no method of adjustment built in that keeps the lock-up tight when this happens.
One quick fix over the years was to peen the barrel threads so that they would engage tightly enough to take out any "slop." If this isn't done correctly, and it seldom was, the barrel will be misaligned, and essentially ruined. You can have the threads milled down, built up through welding, and milled to correct dimensions again, but this is damned expensive.
The takedowns are prone to siezing, or basically becoming welded together after years of being together. I've seen guns that show evidence of being taken apart with two monkey wrenches!
The rotary-spool magazine is a marvel of engineer. It's also a nightmare to put back together if you take it apart. You need to be an octopus. I had to give mine a thorough cleaning once. It took me 20 minutes to disassmeble the magazine, and over 4 hours to get it back together. I ended up making several wooden jigs that helped.
Finding a correct E version stock is probably going to be a bit on the difficult side. The new stocks won't, I don't believe, fit the older guns.
Finally, the .300 Sav. cartridge is a great little deer number, but it's not without it's peculiarities, as well. It has a very short neck, meaning that proper bullet tension is an absolute MUST or else you'll get bullet setback in the magazine.
Because of the short neck, and the relatively limited powder space, the heaviest bullets you normally see loading information for is 180-gr. But, in my opinion, this is really too heavy for this cartridge. The .300 Sav. absolutely SINGS, though, with bullets in the 150 to 165 gr. class.
Another feature of the .300 Sav. that can be something of a pain to deal with is the very sharp shoulder. Die adjustment is absolutely critical.
All in all, though, the .300 Sav. and the 99 rifle is a wonderful combination.