Once I had the split line between upper and lower cowl defined It allowed my to locate the sky bolt flanges that I'm using along the upper cowl/firewall flange. one thing I forgot mention last time regarding the cowl split line. My original plan was to trim the split line so tat it would be parallel to the longeron line just for aesthetics, but I didn't have hardly any extra to cut off so it was a case just true the edges up and you get what you get & don't throw a fit. I think I took about 3/8" one side and almost nothing off the other. Anyway, back to the sky bolt experience; Skybolt suggests 3 1/2" maximum spacing for these and thats what the flanges are really designed for. Based on where my cowl split Ines are, that was going to result in the second one up pointed right at the upper engine mount bolts. I think that they probably would have cleared, but I know some guys have reported interference issues here. Skybolt mentions that you can adjust spacing to account for tis if necessary. Also, some people have issues with the cowling pillowing between the fasteners when the cowl is pressurized, and the sky bolt literature recommends a reinforcing strap adjacent to the firewall fasteners. So, for a couple of reasons, I elected to modify the spacing. This took absolutely forever. What I ended up with was a 3" spacing for the first two, then 3 5/16" for the rest up to the centerline. Good clearance, symmetrical spacing, and overall just aesthetically pleasing and a nice tight spacing that will hopefully prevent any cowl pillowing. There were a couple of places where this spacing required modifying the flanges by cutting off the overlapping feature so that the spacing would come out right and still work with the rivet holes in the firewall flange. Wherever that happened, I added strap doubler under the flange to pick up extra rivet holes and really tie these together. Ive got this entire assembly trimmed, countersunk etc as required and it's all clecoed back together. Tomorrow I'll rivet this all together.