I have an old holley 650 dp and was wondering can demon brand jets/ squirters
be used on it since, I have them laying around. Thanks , tried a search no
luck.

The jets are definately interchangeable.

The squirters I'm 95% sure they are. The Demon ones look a little different but I think they fit the same. Should be easy enough to tell when you put them on and try them out -- if they squirt fuel without leaking they're OK.