I will definitely be replacing any gaskets that appear to be leaking, and I'm going to degrease the new engine and clean it up before putting it in. However, I'm on limited funds (I'm trying to keep this engine swap under $500 including the engine, otherwise it might take me until next payday, and dad wants his garage back lol) so replacing an oil pan gasket and main seals would be an added expense I can't really afford at the moment. I guess I'll have to see how the engine looks when I get it, if there's any damp spots on the engine I'll just have to replace the gaskets that appear to be leaking. Oil pan gaskets are pretty damn hard to replace in-vehicle on the 3800 lol.
I checked out that post, that's extremely helpful and I might have to look in to doing that with the new engine - although, as stated above, I'm on a budget and somewhat limited with time - If possible, this all needs to be done by this weekend.