I am not sure if this will work but I think if do what is needed to kee the Engine From Starting and you Crank the Engine the Valve Rotators on the Valves will Rotate them so you can get a wrench on them.

The Stock 2 Wrench Hazet Set also can have a simlar issue as the Handle will hit the Fire Wall. You might also see if a regular Wrench would work although on the lower Nut the wrench needs a 1/4" Thick head.

People used to recomend several Methods of holding the top Spring Retainer so it would not rotate and that worked till I think it was 2 People over the space of 2 years cracked/broke their Valve Guides.
Not sure why in the last 2 of the 7 Years I have been on the Forum that is happening?

Hunter posted a thread 2-3 Weeks ago with some links. One of the links was on makeing the 3rd Wrench to hold the Spring Retainer.

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84 300D, 82 Volvo 244Gl Diesel