You are not going to have any problems using anti-sieze on an aluminum head if you don't go crazy with it-of course, don't over-torque, and go lightly with the application, just google 'using anti-sieze on aluminum heads'. most anecdotal accounts of people using anti-sieze are positive, and I have used it on numerous engines since the inception of aluminum heads, never had any issues with 'misfires', or subsequent removal of plugs. This is from thirty plus years of experience, but do what you want, Motorcraft platinum will last another 100,000 miles so I'd really not worry once you got the originals out.
And KC don't forget to get back to us to say how it went-we've all been there before, I still remember the first time I removed the #8 in my old 93 and thought it was fu'bared from the sound and feel, only to go back in nice and smooth after i PB'ed the hole-it WAS a sick feeling.