I eliminate the intake manifold end gaskets and use a bead of RTV sufficient enough to fill the space and squeeze out a little. I've had much better luck doing that than using end gaskets on every engine I build. You didn't say what intake gaskets your using so it's hard to say whether or not to seal them. Many gaskets are self sealing while others are not. Most have instructions with them and if they don't look them up on the mfg website and you should find your answer there. For the oil pan I do not know of a 1 piece gasket for the LA. Some guys say the one for the Magnum will work but it won't without adding a ton of RTV in each front corner to fill in a large void where they differ. Personally I like the proof gaskets and use A shellac type sealer on them (Fel-pro blue, Indian head, etc) and RTV Ultra black on the rubber end seals. Anywhere you use RTV sealer install the part and just snug the bolts up till you see the sealer starting to ooze out and leave it set for at least 12 hrs till it cures and go back and torque the bolts down to spec
