I was experemently planning a flight from KBOS to PANC with the PMDG BBJ2, however Simbrief offers one default and a profile to the PMDG. When I use the PMDG profile simbrief says that the aircraft exceeds it's range. With the default profile it spit out a working flightplan. On which one should I rely here?

I think it depends on how you have configured your BBJ. In the FMC you can set up how many AUX fuel tanks and thus how much fuel your aircraft can carry. If you then save your own aircraft profile in simbrief - based on the PMDG profile - and edit the max fuel capacity accordingly, you'll always have exact numbers.

Use awemeter think it’s spelt right on flightsim.to he set all profiles for 737.

I always edit and save airframes in Simbrief.