I doubt anyone will take you up on that job. First, none of the standard 1911 accurizing modifications apply to the Hi Power. Everything would be one off and custom. The cost, time, and effort involved would be excessive. A far better choice is a 1911 in 9mm. Many very talented gunsmiths do this work. David Sams of Cartersville, VA is one of the best. My 9mm bullseye gun he built me on a Caspian frame and slide routinely shot 1" groups at 50 yards from a machine rest.
Of course you can proceed with your plan, but my concern would be some unscrupulous gunsmith taking your money and not delivering on what you expect to receive.