Depending on the maintenance that this vehicle has had or not had, worn rings are less likely than other problem sources that should be checked first. Your plan of attack sounds good. If the valves have not been adjusted in many miles, they could be tight and that would cause some loss of compression and hence make the engine hard to start. The other things that you plan to do are also possibles. Definitely check the battery -- sitting for two years is hard on them. Fuel maybe. Glow plugs maybe. Others will no doubt have some good suggestions.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970