Consider that you need a special tool to remove the lock ring and a special slide hammer to remove the prechambers. Given that slide hammering is involved, the block provides a good work bench. It sounds like you need a new cylinder head. If so, you'll probably find a used head with valves and prechambers. If you buy a new head casting, you'll have to move the good valves and springs. The #14 prechambers can be trimmed to fit the a later casting so you can keep your inejctors.

Sixto
87 300D