I did a zero to PPL course on a guy with a Nanchang CJ6. So 285 hp supercharged 9 cylinder radial engine, VP prop, retract gear and a complex pneumatic system to operate all services. I would estimate that he took about 10 hrs more training than if I had done the course in a C 172/Pa 28. Most of the extra time was used on learning proper engine operation and system monitoring.
I don't think that it should take significantly more time to do the PPL in a C 182 vs a C 172. The one caveat is that the instructor must have experience with the proper operation of a big block 6 cylinder Continental engine and VP props. Time on type would be a significant advantage.