First thing to check is that it doesn't have the 2.4 turbo engine, which is a liability for cracking heads. If it does I would change to a different vehicle!
Or, if you can find a 3L (2779 cc ) head, put that on.
Next, after the service stuff thats been mentioned, put the best suspension on that you can.
Spend the money now, because it will cost much more down the line. Surfs are ten a penny being broken on eBay etc, so it's a buyer's market!
Change the timing belt unless you know it has been done recently, and check the tensioner and idler pulleys for noise and corrosion.
Make sure the radiator has no signs of leakage, check all the joints in the propshafts and driveshafts. Jack the vehicle up and check for noise and freeplay in the bearings.
Check the steering ball joints, track rod ends, all the rubber bushes (I am not entirely sure on the surf setup, as mine has solid axles), exhaust mounts.
Look for any oil leaks, find out why they are leaking, replace seal and take any remedial action.
Make sure the clutch bites nicely, or that the AT sounds fine in all gears, check for any adverse noises or virations from the gearbox.
Check the chassis for rot, inspect the fuel and brake lines, the fuel lines tend to rot where they come out of the tank, and the brake lines in the rear axle area do the same.
Finally, make sure you use genuine parts, or at least a reputable source which sells parts you are sure are OEM (i.e. Japanese; Koyo bearings, AISIN clutch etc)
Let me know if you have any specific issues!