When I bought my bike (CB750) over 33 years ago I was looking for a 500cc or similar when it should be my first bike with license. (I had a Zündapp KS125 that I drove around for a while without license).
At the bike dealer I found my then blue 2,5 years old CB750 with17.000 km's, I fell in love and decided to go for it. It was not too big for me despite skinny body of 178cm and 63kg!! I was happy that I did not buy an underpowered 500cc.
(And very happy I did not buy a Kawasaki Mach 4 (750cc) 1974 I had looked at too. Dangerous to drive when it could work very bad and suddenly woke up with full 2-stroke power and off the road as I heard the guy that finally bought it did.)
I did not have any bike license then. I trained on my CB750 with a friend that had license driving car behind, later behind me on the seat screaming when needed. I month later I got the license.
I was very close to trade it in for a brand new Suzuki GS1000G black with blue stripes (no drive chain issues) 1981, but changed my mind in the last minute. 2 years later close to trade it in for a new Kawasaki 1000J but did not. So, now I still have my CB750....repaired, restored and modified it for thousands of dollars, again!
So, if you want an old bike that you can restore and have fun with, CB750 is the choice when you can find plenty of parts for it.
If you need just a bike and don't want to spend too much money, buy a much newer bike max 10-15 years old with low milage which is much better in all aspects than these old CB Fours. You get a good modern bike for what it can cost to restore, modify an old CB Four. $2000-4000US.
I restore mine because I like my bike and the history I have with it.