Increased displacement means more torque. The B18C also has a block girdle reinforcing the bottom end(the B16 doesn't need one with its near-perfect r/s ratio).

The B16 head should bolt right up, and the sensors should be the same if it's an OBD-II B18C1 block, but I'm not sure about an OBD-I block. You should be fine with your P2T ECM for now if you plan on going Hondata anyway.

If you just swap the B18C1 block in as-is, with the p72 stock pistons, that puts your C/R at about 9.8:1, which is fine for boost with good tuning(which you'll have with the Hondata). If you put your pr3 pistons on the B18C1 rods, your C/R will be around 11.11:1, which is a bit high, especially for anything but moderate boost.

If you want some more power out of your B18C1 block, you can put an LS crank and LS rods in. That would give you the extra stroke and torque of the LS, and would push your displacement to about 1834cc. If you ran the B18C1 p72 pistons, your C/R would be about 9.98:1, slightly higher than with the GSR crank and rods, but you'll still be able to boost well on them with proper tuning. With this setup you'll basically have all the benefits(LS stroke and torque) of an LS-VTEC setup without any of the weaknesses(poor oiling, no block girdle), and you can still boost it.

If you're getting a B18C1 block for close to nothing, you might as well swap it in. If you don't feel like going with the GSR block/LS crank setup, at least run the GSR block. I don't think 210cc more displacement is a waste of time at all.