I would make a list of the machine shops in your area. You can visit them and talk to the owner. Tell him what you want done. Ask questions like what is done to the block getting it back into shape. Ask for references on engine builds he done. Don't forget most important the price he will charge. If you want to use the factory intake and carburetor be sure to tell him. Tell him you want about one stage above stock rebuild. This way it will give you a little more horsepower. Like Vinnie said you want the block cleaned, decked, bored and honed the block with torque plates installed aligned honed. Once you see the price you the machine shop gives you which will be around $ 5000. You will probably want to buy 355 ci 310hp BluePrint engine. GM 355 Engine Specs (BP35511CTC1) | BluePrint Engines
. IMHO just like anything else if you don't do as much as you can you can expect to pay the high cost they want. That BluePrint 355/310hp sounds perfect for your 69 truck.