Since I'm about ready to pop the top onto my new (used) van, I laid out the cut pattern for the van roof today.
For future reference, if anyone is putting and SMB PH top on an RB van body, the hole cut-out starts at the rear face of the B pillar cross member. In other words, you will need to cut the rear flange off of the B pillar cross member when cutting the hole, that's where the cut out starts. If you begin the hole cut out where the B Pillar flange meets the roof sheet metal, the hole will be too far rearward by about 3/4" or so. THIS INFO DOES NOT APPLY TO INSTALLING A EB PH ON AN EB BODY. Those require a transplant of one of the cut out cross members directly behind the B pillar cross member....at least that's the way SMB west does it.
After removing the headliner (passenger van), we laid out the hole cut-out with a sharpie and a pencil, then I drilled small holes at every corner so that in a few days when the top is ready for transplant all I will need to do is connect the holes from the topside of the roof.
I heavily documented the hole cut-out from the donor van; that's what we are using for the cut-out in the new van, and it's pretty much dead-on. The donor van was a 2003 and my van is a 2008.
The critical dimensions are from the rear of the roof to the cut-out so that the rear of the PH roof lands in the gutter properly, but you are somewhat limited by the position of the B pillar cross member and the length of the cut-out.
Here are a few pics of the layout holes......
The first pic shows a layout hole in the rear flange of the B pillar cross member; that's the flange that will get removed with the hole cut out.