Well I finally got the head rebuilt after a little drama. I also learned a lot in the process about degree'ing cams in the process and that Tomei's lobe centerline spec is in reference backwards from TDC rather than forwards from BDC...HUGE difference. Basically I put in solid lifters & solid style tomei 260 cam's, supertech dual springs, new stem seals, metal head gasket, mang/bronze guides, and titanium retainers. When I clearanced the shims, I used the slotted guides on both sides of the rocker arms which required a little bit of machining on the rocker tips. Clearancing the shims was a royal pain in the butt so I just took a long time and triple checked it. I also had my timing cover still on and found that the chain slipped at one point before reinstalling the cams...contributing to the pain of degree'ing the cams and resetting timing. I also did a port match on both sides of the head with my gaskets. After cleaning up the whole affair and addressing a lot of small issues on the motor, I finally put it all back in the car and fired it up about a week ago. I haven't driven it yet as I need to finish the transmission first and that's in progress as I write.
Bottom line the 350z 6 speed is officially mated to the back of the motor using the adapter plate. I'm going to have a hybrid driveshaft made using the donor 350z slip yoke and the 280zx rear diff plate. It measures out to 44" between transmission seal to the diff face for my 2+2 with the way I have to motor mounted in my bay. It seems like I'm going to need at least a 3" diameter steel tube for the critical speed issues on the driveshaft at high speeds.
FWIW, the stock 350z driveshaft (carbon + steel/aluminum) weighed around 13 pounds and the previous 280zx steel 2.5" dia driveshaft about 38" long (not original due to SR swap) was only 6 pounds.
I'm going to make a custom transmission mount to hold up the back end of the 350z transmission and leave room for the exhaust to stay more tucked in.
I made my own backup lamp switch "plug" for the 350z transmission using small female blade connectors shaved down.
Later on I will get a Cable X box and a Kia Sedona ABS ring gear on the differential input shaft to drive the stock speedometer again.