See, I knew you were up to no good!
As you saw, the ES-1A isn't much larger than the Silvia - one of the reasons they're so popular.
Yeah ... that would be a good machine to get for sure for the espresso aficionado ... the only thing that was a deal breaker for me was the plumb in thing. I know ... you are going to say you can get the flow jet and yoyr on your way, Here is one for you ... how about finding a mod to make it a pour over?
I suppose you could switch the rotary pump and motor out for a vibe-pump and have enough room for an internal water reservoir? I know one user who just kept a one-gallon water bottle next to his Bunn in lieu of an internal reservoir. The rotary pumps are rated to suck water from an unpressurized source from 6 feet below the pump. I'd suggest putting a one-way valve near the pump to keep the pump wet when idle.
There's little that's not doable, given time & money, plus a flash of brilliance now & then!