Lapping in a fresh valve can be done.....I have done it....

Just be sure that you use a thin film of Prussian blue fitting compound (Permatex makes it)
Set the valve gently in the seat and tap it lightly.

Lift the valve and make sure the contact is good all the way around the seat and the valve face.

Lapping all the valves would be OK
New seals on the guides..
Just the factory type will do.

The TTY bolts will serve you well.

These engines live the longest at boost levels in the 10-12 psi range
EXHAUST GAS TEMPS IN THE 1000 F AT THE PORT MAXIMUM AT HARD THROTTLE PULL.

The old glow plug through the "Chinery" trick is tough on things....
Be sure you get the injectors gone through and all set to the same POP pressure.

Keeping the pop even is paramount to get a smooth running engine.
Stick with stock pressures......do not be suckered into HIGH POPS.
Tougher on the IP and unnecessary..

Also a nice clean CONE of spray when the injector pops.

Slobbery injectors waste fuel and create high exhaust temps.