OK, you must be talking about cam timing. Get the Haynes, it describes setting the timing properly. IIRC, there are multiple marks on the block for 2.5 and 3.0. Someone else can clear that one up for you, as I'm not sure which to use (I think it depends on which cams you use).
As far as the timing marks on the cams - go to
www.alldata.com and look at the list of TSBs for 98 SVTs, then go ask your local Ford dealer for a copy of that TSB. You'll know which one you need as soon as you read the title.
