I think a 1.8 would be perfect as built the first 1.8 1ZZ Matrix turbo and it worked really well, my power goal was not high, 250WHP, it had zero lag and for the use it was perfect. I would want at least 300WHP and zero lag or next to zero and it would be incredible in this car. It was a fairly simply build, log manifold, 5th injector, etc...
If it was not for being retired and preparing to sell the house, shop, all my other projects and go full time RVing I would of likely designed and built a twin scroll turbo system for this car, I have done it before on another car, manifold took 50 hours to build!
It was a hybrid, equal length, firing order sequence, single WG manifold which I would of done on this car as well and it would of been much more work but I build such things to the highest degree I can. It is not something I could ever make a living at so it would be a one off design I am sure as I had to rebuild the engine mount, relocate the coolers, etc...why half ass something