I think you're not understanding the issue with displacement when comparing to those other motors. It's a 1.8L. K motor, 2L-2.4L. So that's 10+% more volume depending on the K.... let alone the G8 you referenced. There is no replacement for displacement.
That said, Darksol, 11.3 at 123. Fred zust, 11.X at high teens. A once previous owner subarurat did a low 11 on a stock motor even... granted these guys may be exceptions, but it's totally doable without a lot of work. Right out the box, perhaps, depends on the supporting hardware...
Nevertheless, the 1900 won't even sorta fit in the engine bay. It's HUGE. It also doesn't like to make the needed 20+psi boost that's needed to make it worth it. It CAN, but doesn't LIKE to. The 1320 is similar. It CAN make 20 psi, but efficiency falls off a cliff at 15psi and the RPM we make.
Some of you guys are new to this and just discovering all this "new info" that we veteran lotus owners discovered years ago... It's not a knock on all you noobs
. We all had to start somewhere, but don't take our silence in posting ("our" being those of who have been around a while) as indication that nearly everything has been tried, done, raced, blown up trying, won, etc over the past many years. It's all out there on this forum with the search function. Just say'n