There will be an aluminum interior 'doghouse' that will mate with that opening. I've been trying to get as much done as possible that I need to in order to move on to the interior panels. The lack of a transmission adapter is killin' me. I keep searching for a used one but no luck so far.
It's surprising how much heavier the body is when the Lexan is there. I'm constantly having to raise & lower the body whenever I'm fitting stuff. It's a real pain in the butt when you're doing it by yourself and you need to grab the supports (and put them in place). I always end up holding it up with one hand while I line up the poles.
I haven't gone to many car shows this year but I'm tempted to put it in a 'PROJECT IN PROCESS' class at one of the remaining shows. I think it's still too rough but it'd probably draw some attention. Maybe I could land some leads on parts I still need if I did take it.