Glad you got 'er done, Bill.
I think car guys like we all are understand instinctively that plastic and exhaust gases (right from the exhaust ports, at that) are a bad combination. I don't care if coolant surrounds the EGR passage, that engineering solution makes no sense. The all-aluminum Vega cylinder block springs to mind.
I was initially conflicted about the sleeve, wondering if the metal sleeve in contact with the plastic (even though a thin coat of epoxy) would eventually burn through yet again.
For that reason, I used stainless steel, because it doesn't transfer heat as well as mild steel alloys and further, is not eroded by exhaust gases.
I also initially had to think out how to ream the EGR passage. As I'm using reamers and not a drill, I have control. My initial thought was to make the stainless sleeve a light press fit, but then I worried that the sleeve might expand enough to crack the plastic.
So, I now use a reamed hole that'* about .010 larger than the sleeve and goop up the sleeve really well with epoxy. I also roughen the inside of the EGR passage and the outside of the sleeve so that the epoxy has enough keyways for the repair to remain (hopefully) permanent.
Guy, there aren't any failures yet, and I have 30K on mine, but keep in mind we're all part of an experiment, that thankfully seems to work so far.
By the way, when the EGR passage is reamed out to .885, the openings to the coolant passages are quite small and at the 9 and 3'oclock position. I suspect that this is how the new Dorman was construcuted-with additional material in this area.
If that'* so, it just means the Dorman will last a bit longer before failing.
1999 SLE K engine