Main thing body wise is the rear arches, they rust badly. Also check under the rear carpet under the seats along side the wheel wells, rusts there too.
Check the chassis around the rear wheels, also where the leaf springs attatch.
Turn up out of the blue to have a look, if possible. Then start it from cold, check for oil patches etc. Do all the usual rad cap, oil cap. Also do it whilst running, checking oil cap and power steering fluid reservoir.
Take it for a spin, check all gears, and water temp range.
Lock hubs then try 4wd forward and back.
But for £450 you wont be getting anything superb.
But have a damn good look underneath, and tap around with a screw driver. As the chassis often rusts from the inside out.