I have one of those Homelites. Actually, I have a couple, but I have one that works ( I have a lot of chainsaws. I like chainsaws....). Someone gave it to me a couple of years ago in need of a little fuel line TLC, and I spent a couple of hours tuning it up. My usual saw is a much newer and nicer big Stihl, but I keep one of those Homelites at my lake camp, and whenever I need to cut something I can pretty well count on it working.
It's hard to decide whether or not to put money and parts into repairing one of these if it's not working, but if it is working or almost working, I'd say it's worth keeping. It's a good quality saw, much better than the homeowner grade junk you buy nowadays. Power is adequate, and though it's a little heavy by modern standards, it's no monster, and I think a little weight makes it safer to handle. It takes a rich mix (16 to one, I think) so it's a bit stinky, it has a manual chain oiler which you have to remember to use, and it does not have any hint of kickback protection, but if you're careful it will cut lots and lots of wood. I put in a lot of hours on one of those Homelites as a teenager. I'm still alive and have all my body parts, but I must put in the usual caution here that this saw dates from a time before window screens came with cautions not to use them as a baby gate, and before the peanut packets warned that they might contain nuts. It's a serious woodcutting machine from a time when it was expected that the user would take it seriously, learn to use it, and accept the considerable risk.
If you do keep it I recommend getting, if possible, a modern bar and chain. A roller tip bar and a newer style chain will cut a little easier and kick back a little less than the old round chipper chain. If you do keep the chipper chain, keep it deadly sharp to avoid kickback (see Jeepm@n's caution there), and also because it will pull crooked when it gets dull, and if you have a plain tipped bar it will heat up and go slack and pull even worse.
I don't know about the precise model of McCullogh there, but I think it's new enough to be past the "golden age" of McCullogh. Some time in the late 60's they came out with some new models which were very light and powerful for their size, but had a great tendency to fall apart and to leak irreparably. If it's working, it might be worth keeping going, but I wouldn't put much effort into that one.