couple of things. I would seafoam the engine and intake first. i would also get the gasket that fits the oil fill cap...it is brittle, leaks..and looks like its part of the unit but it is a gasket. id also get the throttle body gasket and the ICV gasket. I did not see a new pcv valve listed.. while throttle body is out take it apart and clean the ICV valve correctly. the plastic loom cover under the driver side gets very brittle and may brake apart on you. i wrapped my wires in "rescue tape". this would also be a good time for new plugs and wires. if it can sit overnight after putting on the new valve cover gaskets. go back and recheck the attachement bolts of valve covers. I did on one of mine...and they took more torque. speaking fo torque....correctly torque the valve covers down. they will snap if you dont and on the forums....aftermarket valve covers are junk.
As far as using aftermarket....i have had no problem with quality aftermarket on my past .2 vlave cover jobs...but i never owned the previous two over 20 k. ( totaled one and sold other it was a POS) so cant speak of longevity of aftermarket on these parts. my current one got new yota with previous owner about 35k agoaccording to receipts that came with rig.
my first I used Oshino....supposedly origally supplier to yota...but cant find again....the 2nd i went with napa mostly cause i was in a hurry and did not want to order....and most napa parts have worked good for me. but when its critical or internal i go yota