15x6.5 rallye's came on 1975 and up B body Chargers.
The wheels themselves are somewhat easy to find as everyone wants 15x7.
The trim rings OTOH are extremely difficult to find. 15x7 wont work and most 15x6 rings look bad.
IMO, if you must cut down trim rings, get some repro 15x7 and sell the 15x6.5 to someone who needs them.