I was a driving instructor Porsche for a few years in the mid 1980's in Germany.
Here's my two bits. I would start by reading Vic Elford's Porsche High Performance Driving Handbook. It's the bible for the 911/930.
You drive 911's differently than other cars. So, you need to find an old crotchety instructor driver that remembers when the 930 was the absolute best thing going and can show you how get the most out of that car.
Taking driving instruction from someone in a Corvette or a Mustang or a Formula car may be fun, but it is like trying to learn to fly a real airplane by flying video games only.
Although racecraft can be taught in any car, I don't think that's what you're after.