7Age, Halp

Looking at doing a 7age swap in the future, most likely a silvertop 20V

Now, I already have a 7afe, in my AE112, what do I need to make it the 7age. research here says adjustable cam gears, a fancy timing belt with 1 extra tooth, and the 4A pistons.

First off, why do it need the 4A pistons, that's kinda annoying for me as I don't really want to muck around with the block too much, but if its necessary then I guess I'll do it.

What else is needed for this to work, what special things do I need fabricated and what can I get away with keeping standard.

Also, wiring, my stock car is OBDI, I'm guessing the silvertop is OBDII because of the VVT, so would the stock ECU for the silvertop work or do I need to make my own ECU/get one made for me?

Any help is appreciated, and yes, I did message that guy on Facebook who has done this and such, no need to post that link here.

Cheers!