Jmo, But were it me and i had the cash, I'd nail it before someone else does.
The originals are only going up in price. That one is a good example, and will be fairly
easy to bring back to stock, if that's what you're intention is of course.
Mine was in just about the same condition as that one when I bought it in 1998.
I figured I'd just ride mine till it died, and assumed that parts were probably hard or nearly impossible to find. Then, i got a computer and discovered the wonderful world of Ebay. Things started snow balling after that, and I couldn't stop. Once one of these gets in your blood, you can't get it out. If that one runs without major issues as is, I'd suspect you'll be happy with it. Check for rust in the tank, and for oil leaks from the cylinder head area. Warm it to operating temp and ride it. Hope it meets your expectations for a 40 yr. old bike. A really nice gesture for your dad. My previous bike, a red '75 cb 750, I used as partial trade in allowance towards a brand new 1987 escort wagon. The car dealer gave me a whopping $350.00, and the bike was sold to one of the salesmen at the ford dealer, before it left the parking spot I parked it in. Twenty two years later, and not looking for a bike, A co worker told me about this one...Chained and pad locked in a neighbor's front yard. The price was 600.00.
We got him down to 450.....and so it goes.
A shameless display of pride. But it's fun, and I aint getting rid of it.
i got 3 bikes, but this one is my favorite.