Pontiac Parts Are Pontiac 400 Motor Parts Interchangeable With Chevy 400 Parts?

Are Pontiac 400 motor parts interchangeable with Chevy 400 parts? - pontiac parts

I recently purchased a 78 Trans Am with the population of 400 cars. I was looking for parts for them and some are 400 and some are Pontiac Chevy 400th Are they the same? R GM I know, but I just want 2 Make sure that before you buy a handle of $ 400 and many others. We also know of any website all the good performance of this car?