To add, for after you resolve the above-mentioned question about tools
If you are not replacing timing belts as part of this job then your list has most everything needed. Only exception might be a valve cover gasket if your engine does not already have the one-piece neoprene rubber reusable gasket. The 4-piece cork and rubber sets are single use only. The 1-piece gasket is far better so if you need to buy anything that is the one you want. As you are probably aware you'll also need intake and exhaust manifold gaskets, as well as 6 new of the injector heatshield sealing washers that you are very familiar with by this point.
Good chance to install fresh glow plugs while access is easy -- at least replace #5 and #6 with new Bosch DuraTerm. The front 4 are relatively easy to change later if you want to save the expense. Fresh overflow hose for the injectors is always good too.
Valve stem seals: not sure but IIRC the D24 series engines only ever got valves with 8mm stem. Around the late 90s VWs 4cyl diesel engines changed from 8mm down to 7mm (weight reduction I think?). Not sure if that ever happened for the 6cyl line though. It is possible that 7mm valves and guides could be retrofitted during a cyl head rebuild so that might be the only reason. Probably only way to really be certain would be to take it apart and measure. But, OTOH the valve stem seals are not common for leakage on these and might not be worth changing unless you are going the full distance and having the head fully redone with new guides as well (those are the more common wear area). If you are planning to just clean it up and bolt it on then the effort of disassembling the valve train to change the stem seals might not be worth it.
Headgasket: there are MLS (stainless steel layered) headgaskets available for the D24 that are more durable than the original composition type. In an ideal world the MLS gaskets are preferable. Here in North America the MLS type are very hard to come by these days, as our only source for those here was Volvo dealers which have stopped offering them. But availability may not be a problem for you in Europe where there are aftermarket sellers of the same part (Reinz/Elring?). MLS gasket does require a higher standard of cleanliness and finish quality on the cylinder head and block surface, but that is achievable, just be aware of it.
Head studs for these engines are available (ARP and Raceware market them here, maybe others as well where you are) at fairly high cost. They provide more consistent clamping force and arguably increase potential for holding up under big power increases on turbo engines. Arguably easier to work with as well during installation/alignment of head to block. Combination of head studs and MLS gasket is probably the most robust setup of all and probably worthwhile for those who are pushing the limits.
That said, the regular old style composition type gaskets and TTY bolts seem to hold up very well for most of us on stock or lightly turned up engines, PROVIDED the cooling system is maintained in good shape and the engine is not overheated. Head gasket failures are rare except in engines where they are provoked by overheating. So if that is what is affordable and accessible for you, then you can use it with confidence and expect good results as long as other basic care is done. The MLS gasket possibly, and the studs almost definitely, would be unnecessary cost and overkill in a NA motor.