Thank you so much for the appreciation, it means a lot Regarding the radiator, this particular radiator comes with a 1.3 Belta/Vitz so I hope that it should be enough for this engine as well. The Honda City comes with a larger radiator but the Honda Fit that comes with this engine also has a similar sized radiator to this one so I believe it should be enough. Right now it's working really well, but the real test would be when the temperature outside is at its peak and the car has its ac on in slow moving traffic. I'll report here once it has been driven in those conditions in shaa Allah. Yes, I will soon get the spring clamps, the ones that I had were not of the correct size, I'll search for the correct size from junk in shaa Allah.
Regarding the air cleaner box, I've tried the r18 civic one, the original one that came with this engine, another Toyota one that I already had at hand and a few others as well. But none of them worked, mainly because of two reasons, 1) The transmission side mount bracket is larger than its normally is so it doesn't allow a tall air cleaner to sit in the space, 2) the top radiator bar curves towards the back and the engine is very close to it so I wasn't able to install any of the filters boxes, the only air cleaner box that could almost be fitted was from a Nissan March and other 660cc engines, but since those are smaller engines, they wouldn't have allowed enough air to move through them for a bigger engine and I also wanted to install a filter box whose filter would be easily available for at least a few years.
So what I've done is, I've used an air filter from the Honda City, and built a box for it myself. I'll be sharing photos of it in a day or two in shaa Allah along with other updates.