The manufacturer of the epoxy don't recommend epoxy-on-epoxy without roughing up the surface. So i don't think i'll be doing that. However, i saw (and touched) a part that was first sandblasted and then metalized with zinc in their "hot sprayed process". It was like touching grit 180 sandpaper! The told me that paint sticks extremly well to this surface, so i think i'm going for sandblasting + mild metalization. I'm convinced that the EG will get a very good mechanical grip into the surface...and i don't have to worry about the rust...
The only "teoretical concern" i have is that i'll be having a zinc layer between my steel and the EG...i'm not sure if it will have any (real life) impact on the transfer of vibrations...or the long-term binding of the steel/EG...any thoughts on this?
/Thomas