Very interesting.

Definitely has a third party memory upgrade. You also mentioned it was using a 800K floppy drive, so that would mean the ROM has been upgraded as well.

Not quite a Mac Plus, but not a Mac 512K anymore either. The Mac 128K and 512K are inherently defined by their memory. Like was mentioned earlier, the 1024K of RAM may be helping you out more than you realize.

That being said, you have a very unique machine there. I've never seen anything quite like it, but other members on here may have.