I ended the last article saying I'm ready to cut...

not quite yet. I forgot that I also need to have an idea where the longitudinal horizontal split line would fall on the fuselage. This will be important in order to determine the place where to put the intersecting bracket that hold the CLock fasteners. The manual mentions that ideally, the CLoc would be in line with the side CLoc's that hold the top and bottom cowling together.
No better way to measure a straight line on a non flat form than a laser level. 

I made sure that the airplane was still perfectly level on the longerons and then positioned the laser level on a tripod so that the front of the laser line barely touched the front top line of the bottom cowling as illustrated in the image below.

On the rear side, I checked the position in relation the two marks I made defining the overlap while the top cowl was still on.
The green laser line is not really in the middle of the overlap. Instead it's more towards the top. 
I do have to cut at least a little from top and bottom as the edges of the mold are rough. So the closer this line is in the middle, the better it will be.

In this image I also positioned the side bracket which should align with the horizontal front row  of brackets. There will still be some leeway once the cut is made but I wanted to be close enough in order to determine the spacing and layout of all the other brackets.

I may decide later on to move a little below the green line to be in the middle of the overlap. This would create an angle that's only a couple of tenth's of a degree between front and rear. Again, this would probably disqualify it from winning the Grand Pize at Oshkosh, but I can live with that.