Those are some nice pieces and the timing belt will not allow the timing to change like a chain can. But, you must replace the valve spring with a lightweight checking spring and check the piston to valve clearance with a dial indicator or with feeler gauges to ensure the clearance. By turning it over on the stand, you do not know if it is .000" or .200" or anywhere in between. It will rotate for both, and you could possibly still be touching the valves and still be able to rotate it. The clearance decreases with increased rpm's and heat, so that it why it is necessary for the .100" number.
Bill M