What is that behind the riser? Looks like a glock mag.. if that's the case (assuming you were using it to prop up the weapon) and it isn't actually part of the riser then yes. Just about any BUIS will fit. It needs one picatinny slot and the tongue space that is just above the charging handle.
You'll end up with a lower 3rd co-witness with 99% of the BUIS available on the market. If you want an absolute co-witness, you'll have to lose the riser. Looks like the QD arm is already installed on the EOT, so it wouldn't be too much to drop it to an absolute CW if that's what you want.
The problem I see is that you will need to remove the EOtech in order to use your BUIS. Yes I also see it is on QD mount and could be removed. With the riser you have it looks like your BUIS will look at the controls if the EOtech is not removed first. Talking with GG&G, they said the reason they made there QD to add no heigth was so there BUIS could look right through the EOtech. Just my thoughts.
I see now where the riser itself might be too high. There are other EOTech specific risers that give the lower 3rd Co-Witness I was refering to, but hell give it a try. But I can tell you, the last thing you want to be doing to pulling off the optic when you have to go to the BUIS
Anyway.. I guess I would be curious about the reasoning for the riser in the first place. Is there another optic that is put on it that needed the height or is this just something that looked or felt right?
Regardless I know at least the ARMS #40L/SP and Troy work on just one slot and the tongue space.
I was sent the wrong lower, I ordered the one with only the "safe" and "fire" markings. I was sent the one with the additional "burst/auto" markings.
That rifle is my very first build. I did not want to go through the wait and hassle of exchanging the lower, I already had all the lower parts waiting to be installed/assembled. So I kept it and used it for my build.