there is no knock sensor. who ever said that, is wrong.
not only does the block not had the sensor, there are no wires for it, and the ecu doesn't have a pin for it anyway
the Y8 head and IM are better than the z6 by a couple ponies, but its harder to wire, being obd2.
I don't know if the CX is usable for a mini me though. Here's why: the cx has 8 valve piston, the z6/y8 head is 16 valves. the reliefs in the pistsons are not there for the extra valves.
While it was done on the 4th gen HF by Cory, and that is the article on here, without a piston swap, im not sure it can be done.
EDIT:
now, i read this on h-t
"However, the D15b8 (Civic CX) engine, which is almost identicle to the D15b6, is also a 8 valve engine, but I am for certain it has 4 valve reliefs per piston. So I dont see why you couldnt do a mini-me on one of those."
so perhaps, its ok afterall. the only way to find out- is to pull your head off and check the pistons.