Steve,
Welcome to the Forum.
You will find a lot of help here.
I would try and find a period engine for your car. A ‘71 2.2 T would be the most correct but a 2.2E/S or 2.4T/E/S would be fun. Although some disagree, a 2.8S is about as much torque and hp your Type 911 transmission will tolerate and have reasonable longevity. You can build a 2.7RS or 2.8S and have it look as if it was a ‘71T – a real “wolf in sheep’s clothing.”
If you decide to go bigger, a 915 transmission is in order.
Your 901/01 can be a standby for a while but eventually should go to someone needing that engine for his ’66 911.
Tell us more about the car.
Best,
Grady