Yes, i looked into using the larger holset HX35 and I still have it but i found some builds where it failed miserably. Very disappointing. And he was fueling it like a mofo! saw something like 4psi before it was reving way too high.
I am surprised, bugnut, that you are sticking with the smaller 1600cc block. I think the 1600cc block with the 1900cc head would make a really fun NA because of the good flow of the head. (having had the 1.9/1.6td and now a full 1.9aaz)
the 1.9 block is much sturdier. bigger rods and pistons. If you have access to a 1.9 bottom end it would be interesting, as i saw, for you to see the difference between the half breed and a full 1.9.
I feel like the full 1.9 makes much more torque but the half breed reved really really fast.
the 1.9 in neutral revs like a car where as the 1.6 bottom end with the 1.9 head on it reminded me of a weird sounding motorcycle. it revs QUICK and i was able to see about 3 pounds just reving it and thats with the T3.
I'm also starting to feel that the T3 is too small now as you did (plus mine is very old a dying slowly). My friend has a couple brand new JDM turbos from the WRX STI's im going to look into the flow charts on and see if they would be suitable. I would have to buy two so if they turn out to be a good match i'll let you know and maybe you'd want to replace the T3/k14 or what ever you go with with one.
Just a little add-on here;
These pumps and injectors will always supply an ample amount of diesel creating a black cloud. You should always make a cloud with and IDI unless you're running like a 175 shot of nitrous at it. ok maybe 175 is a bit big but you know what i mean
black isn't bad.