If you're gonna put a different engine in, you might as well drop in a 3L instead of the 2.5L. I think you can get an almost-new one for around $700US from an Escape or a Taurus or something. Then add on whatever they're gonna charge you for labor, and a few mods if needed. Search the 3L forum for more info, and read a bunch of the posts to get an idea of what's involved.
I think the standard 2.5L is rated at 170HP. Pretty much all of the cars' specs are on the site here somewhere or another. Most of them should be in the FAQ section and/or tacked to the top of the appropriate forum.
What all are they saying is wrong with your current engine for it to cost so much to fix? Is there internal damage, besides just the cats being plugged? On the SVTs, there are three cats -- one on each downpipe from the front and rear cylinder banks, and one on the main pipe on the way back. I think the non-SVT Duratecs are the same, but I wouldn't swear it. Replacing three cats will add up, but that alone shouldn't come near the $2500 range!
Oh, and Welcome to CEG!
Marty
