Are you pulling it? That will save you some bucks. If that's the case I would think you could get it done for under a grand depending on where you live and what upgrades you want/need. Here in the SF Bay area things tend to be more expensive than say around Sacramento. But some shops would be high volume shops and would rather have a 350 ready for the customer so they build them on their time, saving you money.
Get a parts list from whomever you get a quote from, and also find out the warranty and list it here. The trans gurus here will be able to tell you if it's a decent quote based on parts used and labor, which is much easier than pulling a number from thin air on how much it should cost.
That's just my 2 cents worth.