You can't use the F20B pistons, they're not the correct bore for the B20 block.

As for the head there's not much point in getting an ITR one if you plan on replacing the cams. The intake manifold, throttle and mild porting job on the combustion chamber are slight improvements over a B16 head but nothing amazing. A B16 head with JUN III cams would be a better idea, or hey if you want to run the ITR head with the JUN cams go for it. The cams are a big difference over CTR ones. The CTR cams are essentially identical to the ITR cams.