How difficult is a cam swap?

The new plan is reseal only. Cams always sounded easy, until now. With the condition of the engine I didn’t plan on measuring a bunch of stuff, because even if I could confirm something was off by thousandth's like a spring, I don’t have the capacity to resolve it.
I have to also expedite the process as the garage space is not mine. Is advancing the cam without checking valve clearance a bad idea? I watched a few videos about it, and they don’t mention it. Apparently magnum 5.9 cam is 10° retarded from the factory.
Right now I am at a stand still over the timing cover,balancer set up. I won’t take it apart until I know for sure what parts I need to mix, match, and buy to reassemble it la style, the cheapest way….and then of course advancing the cam would make sense if I wasn’t a tard.
Thank you all for the replies guys, I really appreciate the insight.