I expect that you would have to pay more than that if you don't do any of the work yourself.
If I was going to overhaul a 289 I would take it apart, inspect everything myself visually, then have the crank, rods and block magnuflux inspected. Typically they all will have been rebuilt at least once previously, so the bore is likely already .030" or .040" oversize. Once I have determined the existing bore size I would decide if I needed or wanted the block to be sonic checked. This is something that requires skill and experience. It is typically not needed for a 289 that is going to .040" or less, and as I said before, I have bored several to .060" without doing it. Very seldom is a block not rebuildable, but it happens. Crank bearings can be bought as much as .060" undersize but you are more likely to find it will clean up at .030" or less.
To cut to the chase, I would have the boring and cleaning and cam bearing installation done by the machine shop. I would let the machine shop resize the rods, check them for straightness, replace the rod bolts with new ones from ARP and install the pistons on the rods.
Cylinder heads, unless you are after numbers matching correctness, I would just buy a new set from Edelbrock and paint them blue. You can easily spend $1500 having the originals rebuilt. They typically need new seats, guides, valves, and all hardware.
Everything related to the camshaft needs to be new. Lifters, rocker arms, pushrods - all of it. Rebuild the water pump and carburetor and fuel pump. The starter and alternator too.
If I do all the assembly work and rebuild all the accessories myself it can cost me $3000 - $4000 to do a 289 or 302 properly. It's just about the same cost to buy an overhauled 302 crate motor.
Thanks for the replies. I am now leaning towards what most of you said - the mechanic is either not capable or too lazy to do the full engine overhaul. On the other hand I found them quite well specialized in the classic US cars, they are well known in my area. Also they are doing good with the maintenance to a 390 big block in my '64 tbird.
How about the costs? What do you estimate for this type of engine overhaul? Would you expect some 3-4.000 USD including all the parts and labor?