I'm assuming you are using these for the front ... only if the 944T rotors are from the Turbo S (AKA 928S4 rotors) 302mm x 32mm ... its the 32mm thickness you are looking for as the 993T front calipers work with a 32mm thick rotor.
Any less and the pistons may overextend as you brake when the pads are almost worn out, risking dropping the pads out of the caliper
The 993T front pads will not fit the S4 rotors well .. there will be pad 'overhang'. I suggest biting the bullet and getting a set of matching rotors
Sandeep