I just want to say that it’s posts like this that make this forum so great and the Land Cruiser community so unique and special.The short fuel (vapor) hose on top of the throttle body, if original will likely be hard as a rock which will need to be replaced IME. Have some bulk Toyota 3.5mm vacuum hose on hand to replace vacuum hoses that area. You'll also need a new Throttle Body gasket.
If the heat control valve on the firewall is the original it's past time to replace it
and with the valve cover off there's a bit more room to dig into that.
And while the valve cover is off is a good time to super wash the oil baffle box area as sludge/varnish can build up inside.
Ask the mechanic to reseal the half moons on the front of the head which need to be removed, cleaned, and resealed using the appropriate FIPG.
The intake plenum (inside) can be cleaned up some with the TB off.
There is an EGR gas tunnel that can become clogged with carbon,
a pain in the arse to clean with the plenum still attached, but it can be done.
If time/money is not a concern remove the upper half of the intake plenum
and have it hot tanked in an aluminum safe cleaner.
As mentioned previously, good time to clean the Throttle Body, but not just
the throat and butterfly, there are multiple vacuum ports that can get clogged up along with the IAC valve port. To clean the TB completely it's much easier to remove the cables and clean it on a bench, but then more work to reattach the
cables afterwards. Mark the cable nuts with white paint before loosening and/or measure their location.
And if you want to earn your LC OCD gold star (and watch your mechanics head explode) while the cables are loose is a good time to repair the rubber covering on the cables which by now is likely peeling on at least a couple of the cables. You can use two foot sections of 3M dual wall marine grade adhesive lined flexble 1/2" ID heat shrink tubing which can be slid over the cables then shrunk using a heat gun to cover the exposed cables).
Here's a parts list (use only Toyota parts except maybe for fuel hose or spark plugs):
Valve cover gasket
Spark plug tube seals
PCV valve grommet
Throttle Body (metal) gasket
IAC valve O-ring (if the IAC valve is removed to clean)
Air intake hose
Water bypass hose (formed hose that runs from the TB to the head)
Water bypass hose (straight short hose runs from the TB to a small metal pipe)
Bulk 3.5mm Toyota vacuum hose (three feet minimum)
One foot of bulk fuel hose or cut to fit Toyota fuel hose
Replace all 13 valve cover bolts if old/crusty
Heat control valve with new hose clamps
Six spark plugs (Denso Iridium TT are good for 100,000+ miles)
Also good time to inspect and rewrap the main engine harness which runs close to the EGR pipe. At least wrap with some sort of heat insulation material/sleeve and hang it back up if it's dropped down. Gently ask your mechanic to be gentle when handling the main engine harness as the wires are known to get brittle with heat/age and he/you could end up with shorts afterwards if the harness is treated roughly.
Probably forgot something.