It worked good. I used four gallons of west systems, I would pour in the epoxy mix (epoxy, powder, and portland cement to slow down the cure rate) about a half gallon at a time, then cram in lots of fiberglass matting then repeat, it took about three hours, after about five hours it was cured. I waited untill it started to kick and then redrilled all of the holes in my transom before it got real hard. There were no voids, and the transom is solid as a rock. I also drilled some holes in the transom from the outside before I poured it so I could see the epoxy ooze out, once I saw it I plugged the holes with a dowl rod. Then I ground it all clean before it got real hard to save time. Now I just need to sand it, paint it and install the motor. I will post some pics later when I have time, I didn't get as many as I wanted because once I got started it was a race against the clock, and my hands were so nasty I didn't want to touch the transom.
All in all it went well, I had about $450 in materials and 10 hours in labor. I am pleased with the results. ;)