67 A/C heater box rebuild and install help

So dad and I are almost done with the ac box and heater box. There was a few places in the fiberglass boxes that needed repair.There was a hole in the bottom of the pass side fresh air box(very common). And then there were 2 places where the clips that hold the 2 halves together that was broken. I bought a roll of "tech steel" and the stuff worked great! Here is the link
https://www.acklandsgrainger.com/AG...balProductDetailDisplay.do?item_code=NLS16002

I didnt replace every gasket or insulation that was in the kit as I didnt want to risk damaging the evaporator and it didnt look that bad other than a few leaves in there.

The new heater core wasnt 100% accurate on fit, so it required enlarging the 4 screw/mount holes a little bit, as well as the small steel plate with the 2 holes for the inlet/outlet required enlarging the holes a little bit. No big deal.

Once we repaired the 2 damaged spots where the clips holding the 2 halves go, we were ready to put the halves together. Considering there is 11 clips holding the box halves together and how hard it is to put them on, what we did was reduce the tension on them. I simply tapped them a little bit with a hammer so it "opened" them up some, it made them much easier to put on. Where we repaired the 2 areas with the "tech steel" we didnt bother to put the clips on, we didnt want to risk breaking the repairs, plus we figured having 9 out of 11 clips would be good enough.

Sorry for not taking more pics, I did take a few but they turned out lousy and wouldnt be much help.

I have a question though, we are looking at the 2 boxes and considering they are only held together by 1 bolt/mount plate in the middle, can these 2 boxes be installed seperately?? Or do we have to bolt the monster together and then wrestle with it??

Thanks
4spdragtop and ragtops Pop