1 piece would be stronger, and aluminum is way lighter, and it looks better. Especially if you anodize them.
so here's the latest update.
I am almost finished with the plate. I still have to mill a relief on the backside, but besides that it's finished. One thing I'm going to have to mention here is that the plans that are for sale on e-bay aren't very accurate. the only thing they actually got right was the centering to the shaft. other than that whan I compared they're drawing to my cmm report most of their holes barely lined up...... just enough so that the bolts would barely clear. Hardly acceptable for me..... So, I'm very happy I went off of my own numbers because everything matches up very well.
if you notice the extra holes in the plate it's because it started life as a fixture plate that I pulled from the scrap heap at work.
and btw can we say laser cut teflon tb gasket?