After going through a set of Pac 1218X springs which didn't handle my cam (HR 232/240, .584/.604), I ended up with a set of Manley Nextek beehive 221438-16 springs. Been running hard for four years now on my 408, and absolutely no issues.
They're not cheap, but there's a good range of LS style double springs that will fit Eddy heads here, and some are pretty stout - probably stout enough for that Crower cam:
Manley Performance - Niche Market - Chevy LS Series
