Ok Easiest why to tell if it is an RH (no need to call it a 250) is if the gear shift shaft also comes out on the right hand side to fit right side gear shift, it is an RH.
The bike shown is an 1975 model so not legal for Pre 75. John Kittle has got one now too.
How do I know these things? I had one in 1975. Two came into Queensland in first shipment and then another 5 or so came in a few months later.
The bike was similar to the earlier YZs limited production based on the works bike. They are not very rare. Also they were not available in the US.
The motor was stronger than the RM 250 A the next year, but the rest of the bike not as good.
If it was restored in good condition maybe it would be worth the money, but not in the state it is in. Also has it got the original wheels etc.