If your father doesn’t have the technical ability to do most of the work, and must solely rely on hired technicians, sorry to say he will fail. A performance specialty shop would require a higher skill level technician, and these guys usually have there own shop.

Tools alone can cost a bundle, diagnostic tools, hand, specialty tools, and lifts. How would you measure your performance work, with out a diano, someone spending money on performance likes to see the results. If he’s a good tech, start as a one man shop with general repairs.