Most start w/o trouble. Especially if mothballed. Check linkage for proper movement, and if sitting many years, flush old fuel
. Start, if everything ok, change oil and filters. More to it if you really want to know.
When young, my extended family
had a business reactivating stored/mothballed ships. I've started diesels sitting 20 years, 200hp and much bigger. Extremely rarely do the rings rust to the sleeves in diesels, but common in gas engines.
Before WWI, mothballed wood ships had hanging bags of mothballs to stop insect damage.