WHAAAAAT!!!!
That's DEFINITELY a 60s race kart! It's worth WAY MORE than $50!! It looks original and intact, too! The McCulloch 2 stroke engine could possibly be sold in the $300-$500 range as is! (please don't, it's way better to keep it with the chassis)
Can we see some pics of the rims? Sometimes those help figure out the brand.
If I were you I'd buy that from your buddy for $75 and not tell him what it is.