He doesn't have the 3.1 engine. Only the 3.1 has the luxury of rocking forward. the 3.4 only has one dogbone mount up top, and no matter how hard you try, the 3.4 engine does not rock forward, (unless your lower engine mounts are already shot to pieces). To get the spark plug wires on the rear bank, above them there is a piece of weatherstripping. Removing it may give you enough room to pull the plug boot. If not, a tried and true method, is to use a cutoff tool or a die grinder to notch the sheet metal above the boots, giving you plenty of room to take them out (that's what I did).
However, there are those of us who would rather not notch our sheet metal.
The book method is to remove your plenium. If you decide to remove your plenium, you will probably need an upper intake gasket, they ususally tear when you remove the plenium.