In the pics with the measurements shown, the entire dash was out of the car including the heater box. I pre assembled everything before installing the dash to make sure everything would go back together ok. This is where I found the problem with the DMT kit.
After getting the proper type hose from Nappa, I was able to reinstall the dash and heater box , then just reach up under the dash to install the hoses onto the vents. Just used a little white grease around the edges of the hose and they slid into place. Completed the job in a few minutes actually!!