440 valve cover leaks???

Well I am looking for opinions on what is the best valve cover gasket for the 440 with the black cast valve covers, and does anyone use a helper with them. Such as: silicone, indian head gasket, etc. The small blocks I have no problems with. I usually use the reusable gray gaskets (can't remember who makes them), but they never leak. Do they make them for big blocks?
I just put on some expensive Moroso thick blue gaskets on and new ARP bolts and it's leaking on the passenger side and possibly the driver side. Anyone reccomend studs vs. bolts?
Thanks for any suggestions.
Highwaystar