So, in all seriousness, I was thinking this was like a home library, but it appears to be a school setup or something similar. That's cool, but this is a long way from a critical viewing environment.
The Mitsubishi was giving up lumens and image quality due to the upward angle and the required use of keystone correction to make it fit the screen properly.
The Epson 3700 will work better than the old Mitsubishi did. It will be brighter, and will be more flexible with the setup.
It's $1,300 on Amazon right now: https://www.amazon.com/Epson-PowerLi.../dp/B01LZZ7O1M
About the only thing that bugs me is that they have a fairly high replacement lamp cost ($300) while other models from Epson, like the 1440, use $99 replacement lamps.
I would expect that you would go through a lamp a year (or so) in a high use environment like that, which will make lamp costs add up. You ALWAYS want to use factory replacement lamps in projectors that you need to maintain the highest reliability from, so that $200 extra will add up over time.
Be aware that all the connectivity your Mits. has really is no longer typical. I see VGA, HDMI, component video, and composite video connected to the projector. That's a lot of connections which have all basically been replaced with HDMI. So, be aware that a model like the 3700 only has VGA and HDMI on it. No component video or composite video is available.
I'm not sure what you are doing for audio in the room, but it appears that there is not audio connection on the current setup, so I'm assuming that's being handled by an A/V receiver or similar.
You will get easy placement with the 3700 which is nice, but I would look at the Epson 1440 as well. The 1440 may not be perfect in terms of the mounting height, but will work from the same distance and has inexpensive replacement lamps with plenty of brightness for that location.