This is assuming I still retain my current knowledge?

Then I'd build it again. I'm not saying I would have had this brilliant idea myself but if I can retain my current knowledge I would be able to build Bitcoin myself since I'm familiar with all the cryptography etc.

I'd probably need someone for the p2p gossip network stuff since this isn't my field. I'd also choose the way of making a formal definition first and then implementing it. And third, I'd implement in Java probably and if I could get a few people on board like 3 implementations in 3 different languages, an elaborate testing setup to measure the implementations against each other.