If you've been offered it for 'half that' you would be a fool not to buy it.

If it wouldn't involve divorce and the removal of my testicles, i'd buy it.

If you can find out the engine and cylinder markings, people here might be able to distinguish if it is factory standard or A / B kitted etc.

A photo of the carbs might also help.

Other than that you've seen a fresh motor be started and ridden it, so you should be aware of any of the normal mechanical issues you should be looking out for.

Be prepared for a diet of pistons and rings, and start looking for spares - a crank, heads and cylinders would be worth having. Also consider where you will be sourcing race fuel from (I'm assuming it comes with carbs set up for race fuel, and some jets for setting it up)?

Get yourself the manual for setting up the power valves too. If it is like my old RS, then it's rod activated and a real finicky bastard to set up.