In the basis of that very vague statement I would question their competence, at least until they give you a verbal or written report explaining the exact current state of the engine and what it needs in parts & labour to put it in top-top working condition.
Let me put it another way. If they plan to present you with a $9000 invoice for rebuilding your engine the least they can do is provide you with a “$9000 story” to justify that invoice. That document should contain as a minimum:-
1. A detailed tear down report identifying what caused the failure and including a description (photos if possible) of the actual condition of all the major components - cylinder block, crankshaft, camshaft, rods/pistons, cyl head, valves, turbo, etc, etc.
2. An itemised list of the required spare parts required for the rebuild, each one individually priced and with information whether the part in question is genuine OEM or aftermarket. If a part is aftermarket they should include info on what brand it is.
3. Details of any external services required for the rebuild. As an example sending the crankshaft out to another shop for re-grinding.
4. Total number of labour man hours and the hourly rate.