I know I'm late to the party but since I just went through this I thought I'd chime in.
Here's what I ended up doing: I used the factory valley pan and sprayed Permatex Copper Spray-A-Gasket on both sides. I bolted down the end bars to hold it in place but didn't fully torque them down. Then I sprayed some copper stuff on both sides of TWO of the FelPro gaskets and laid them in place. The copper stuff was tacky enough to hold them but I used a couple pieces of painters tape as insurance. A dab of Permatex in each corner filled any little gaps. Then I placed the factory 4-barrel intake manifold where I wanted it. Had to be VERY careful to put it STRAIGHT DOWN without any sliding or wiggling.
All my bolts lined up perfectly. No issues whatsoever. My engine has the original, unshaved factory heads and the cast iron intake wasn't shaved either. All original bolts were replaced with new Grade 5 bolts and added hardened washers, all from the local Tractor Supply Company.
Great place for all kinds of hardware btw. Grade 5, 8, stainless, metric, standard, whatever you need. And they sell it by weight so it's easy to get as many as you need of whatever it is.
Anyway, torqued everything down in three steps and VOILA! Done deal and no leaks. BTW this valley pan gasket had been through 2 manifold swaps before I finally settled on this combo. Speaks well for it's design methinks.<br>Hope this helps you or someone else.