EFI 5.0 kit will have very different intake & exhaust gaskets (due to sequential ports) as well as unique rocker cover gaskets & rubber seals to go under the 2 rocker cover bolts on each side that go through the covers. The last couple of kits I've used also included the throttle body gasket - making it a dead giveaway.

I don't know the differences between red & blue kits (with the exception of the neoprene rear main for early reds) as I've only played with blue & black Holden V8s. One could suggest the intake gaskets again could be the way to pick them, as the EGR port shape changed, but the last ones I used (3 years back) were a multi-fit style.