If it's a driver and you're keeping it stock, then get Ford parts. Plugs and coils will actually be something I bet you feel. After that long, coils get weak.
Due to the potential of a head gasket "catastrophe" I wouldn't take too many risks with the plugs & coils. I'm not sure if there are any aftermarket coil packs but if you want to replace them I'd stay with the Ford OEM coils. I'd also stay with the Iridium plugs. I don't think the brand is important but I think that the flame pattern may be. I think the risk to engine detonation is too great to play around with this. My 2 cents.
Agreed we also typically stick with the OEM ignition coils even on high horsepower performance builds. For spark plugs if you are keeping the car completely stock the OEM Motorcraft plugs are great, just make sure to gap them correctly. For performance modified vehicles we'd typically go to a colder plug such as Ford Performance with a tighter gap also.
I change about every 10k. I'm tuned on E30 and after about that long, the gap has opened up enough to start to pick up a small misfire at high RPM. I suppose I could probably just reset the gap in most cases, but if I'm in there, I'm going to change them. $40 and 30 minutes every 9 months or so isn't that big of a deal.