Ok, I've been lurking for awhile now and decided its time to pop my cherry. I'm in the process of swapping the blown 4.0 out of my 2000 xj (auto) for a low mileage 99. Went with the 99 to get the 0630 head. Everything is pretty simple so far, but I have an exhaust question that I haven't been able to find a good answer for.

As we all know, the 0630 head has bigger exhaust ports than the 0331 so the exhaust manifold from the 2000 isn't big enough to cover the ports on the 0630 head. I have, and would like to use, the tube manifold from the 99. Problem is the 99 collects to one pipe and the 2000 has two, which means the downpipe on my 2000 is branched where a 99 downpipe isn't.

So now, after my jeep's life story, here's my question:
Will a 99 downpipe be a direct swap for a 2000 downpipe if I use the 99 header?