I had a 944 NA throttle body done by these folks a few years back. Quick shipping, reasonable price, etc.
Maxbore.com throttle body boring service and repair
Before anyone asks, no, going to a 60mm throttle was not worth any power at any RPM on an otherwise stock 944 NA 2.5L engine.
But I would bet there's some power to be gained on a 3.0L 944S2.