Sorry, I don't have an answer to your question. I tried a few searches but there doesn't seem to be a way to search for "finished interior". Search returned entries with "finished" and "interior", not "finished interior".
For what it's worth, my build, and finished interior pictures, are in the link below.
Hope this helps (a bit).
Doug Vancouver Island, BC
GMC Savana Explorer Limited SE hightop conversion van NEO NAVR 7x16 V-nose aluminum trailer now a comfortable travel trailer
2nd that on Pinterest... and if you start collecting it will email and show you more related. Lots if great ideas. I started a folder on my computer of images for inspiration and ideas on my up coming 6x14 conversion. Also YouTube. Just do a search. I watch them on our big screen TV and it does the same will suggest other videos.
I agree with the others about Pinterest. YouTube also has some great conversion videos. For my build, I got most of my ideas from Sprinter Van conversions so don't just limit your search to Cargo conversions.