I have a Norco of slightly older vintage. Mine had a dodgy steel seat and rubber that were junk. It’s not worth anything as an antique so, yes, fix it up & ride it! It appears that the sprocket on the hub is bolted in place so it shouldn’t slip (mine did that too!)
Naval Jelly does a good job on the rust, at least on the chromed parts. The gray parts, like the seat post and clamp, were shiny when new, but not chrome plated. It’s more of a faux galvanized finish. I got all of those parts chromed on my own Schwinn, so they are more rust-resistant. Keeping the rust away is helped by storing the uni in a place that’s low in humidity, if possible.
For the labels I’m not sure what’s the best approach. One idea is to just try to glue the loose parts back down, using something that’s clear and won’t discolor. You might be able to find replacements also, from collectors. You can try eBay, and also the Unicycle Factory, Tommy Miller.
The Schwinn whitewalls cleaned up well with bleach, though at this age, not sure if that will remove any yellowing.
They stopped being made in 1983 (along with all the unicycles; the 20" and 24" returned from 1986 - 1993 or so. Then another Chapter 11 filing by Schwinn stopped the unicycles again, though they returned for a while in '95 or '96. After that they were “saved” by Unicycle.com, and still available today in their current form. But no Giraffes since '83. I got mine in early 1980. It came with the giraffe on the sticker. A picture of a giraffe, that is. Apparently Toys R Us had a problem with the look of that giraffe, and at some point they switched to the blue sticker you have. Not sure when this transition took place. My 1980 Giraffe also came with the 3 bolts holding the bottom sprocket on. Earlier models had a track-style setup, where the bottom sprocket could spin loose.
Speaking of bottom sprocket, I know Schwinn had made some bottom sprockets with one less tooth than the top one. I purchased one of these from Tommy Miller in the early 80s. The idea was that you wouldn’t get the uneven tire wear of a regular unicycle this way; it would tend to be more evenly distributed around the tire. I’ve had the same tire on my Giraffe for more than 20 year now (yes, low mileage). If yours has one of those, I think it’s 27 on the bottom and 28 on top, it means it’s closer to the 1983 end of production but I’m not sure how close.
In as far as collectible value goes, I think that’s relatively nil these days. Too few collectors. The Schwinn Giraffes were excellent, but this was mostly about the frame, not the other components. Upgrading pedals or seat will make it more functional. Mine runs mostly original parts, though the seat cover is a white one, from Semcycle. I actually wrestled that cover on over an older black one, for a more drop-resistant seat.
Don’t paint it. The Schwinn chrome is super-durable and looks great! Also it probably won’t give paint much of a grip, unless you were to sandblast it or something. Please don’t.
Seat post size:
If I remember correctly, it’s 7/8". That comes out to 22.225 in a straight conversion, but I would get that confirmed before ordering anything. KH seats will fit on top of your post. What people now call a KH mount was originally a Schwinn mount.
I think mine looks pretty nice, though it hasn’t had any TLC on it in quite a while. All the “gray” parts are chrome, so in this photo you can see the shiny cranks, clamp and seat post, for instance. Also I put some BMX Freestyle pegs on it, for hand-cranking. You stand on the pegs and pedals with your hand (or hands).
BTW the one we’re talking about is the one on the far left. I used to use (chrome) rattrap pedals on it, but went back to the original block types for hand cranking.