hate to say it, but if this is your first time doing a swap or intense engine work, don't do option 2. I've swapped a b18a into a 4th gen civic hatch (which is considered an 'easy swap') and it was rough. The wiring alone took almost two years - due to my buddy cutting my stock civic wiring harness off. Option 2 is a bit of a reach for me, even, but this time, I've done 3 years of homework. Unless you want to kiss your car goodbye for an extended period of time, I'd say the b20 or option 1 are your best bets. And even still.. make sure you've got a few buddies to help you out. My best piece of advice with whatever you do.. do NOT cut your harness out with the stock engine. You need every wire in there. Making a new wiring harness from the shop manuals for two different cars sucks ass.

To answer your question, though, I'd say to go with the ecu magic for the knock sensor. Personally, I'm not drilling my block unless someone's willing to give me another one for free. Maybe next frankenstein swap.