Ok David I believe you have more than one problem here so try the check list approach to scratch off things it not. We will leave the 6000 rpm in 5th for the OPP to solve

Smoke under the hood beneath the head on the timing belt side is most likely a cracked exhaust manifold stud and its leaking. A fairly common problem but not entirely cheap if you cant do the labour yourself. The fact the the smoke stopped was the mani heats up fast, expands and seals the leak.

stud fix


The clicking or tapping noise at start up is most likely lifters and when the car warms up and circulates the noise will disappear. From your description though the clicking happened on a fully warm engine after a high speed run. Did the clicking start when you backed off the throttle or when you restarted the car after filling up. If it happened when you were still at speed its not likely to be lifters and could be a lot more serious. You say it was valve train but if the tapping is lower then start saving your pennies for an engine rebuild.