You should snap this cab up in a flash, regardless of the slight imperfections - these cabs are 25 years old now so there's always gonna be something to sort out. This one looks good and is a bargain especially if you can get it delivered for £300!
I wouldn't worry too much about moving it or storing it in a slightly damp environment. I had my OutRun in a shed for 11 years. I just took the boards and the pedal assembly out over winter and stuck a couple of those damp traps in there - the wood stayed damp free. I restored it back to its full original glory
To move the cab, just remove the dash panel and monitor - that's a lot of the weight gone. I put plastic castors on mine to make it even easier to move and keep the cab off the floor..
Go get the cab you've been offered quick before someone else beats you to it - it's gonna get a lot of views in that arcade this week