Ok, so here's what I got regarding a few pics and the stack and reach stuff.
As a comparison, here's my C59 as it sits now, with a saddle height of what I call 810mm, measure to a straight edge across the top. There's about a 5mm gap between the bottom of the straight edge and the dip of the saddle so you could say it's 805mm to the lowest point of the saddle. @Crossifino, this is probably something to consider since you use a saddle with a very big "dip" in the middle so adjust accordingly.
My C59 as I ride it currently with an 805mm saddle height:
Same bike with the saddle jacked up to 855mm, @Crossifino's saddle height:
A pic with my straight edge on the saddle which I use for measurement of saddle height and angle:
Closeup to show the "gap" between the straight edge, versus the actual height I sit at... 810mm to the straight edge, 805mm to the saddle dip where I sit.
Closeup of the stem area:
Closer view of how much I raised the saddle (bottom edge of yellow tape is where it was before raising for photo):
Ok... so in summary...
Up to you I guess... you know your fit better than me. Doesn't look extreme in the photo, but in reality I would need a step ladder to climb up there
I am using a 130mm -6 degree stem with a 3mm spacer underneath the stem and the 16mm tall top cover provided prior to the Acros headsets they're using in 2013. Given that here's some measurements as shown for what you propose:
Saddle height: 855mm
Saddle to handlebar drop: 159mm (see note below).
Saddle setback: 112mm
Distance from tip of saddle to bars (next to stem center): 647mm
Regarding drop, you said you'd be using the deda stem with a -8 degree rise. That will increase the saddle to bar drop by ~5mm over a -6 degree stem of the same length. Plus, I have a 3mm spacer and the older top cover which is taller than the Acros they now provide (but let's ignore the top cap difference for now since I don't know it exactly). So, if you did "slam" the stem you're looking at saddle to handlebar drop of 159+5+3= 167mm. In my mind that is a pretty big drop so I hope your arms are long as you say and you're comfortable with that. Again, you know your fit best.
Oh yeah, stack and reach for @tinozee: Stack: 609mm, Reach: 410mm measured to the center of the headtube flush with the top headset cup. This does not include any headset cover tops, which can vary.
Hope it all helps. Have fun!