If you don't have a lot of money, why waste money on the G23? Stop kidding yourself. You are not going to be able to build it for less than $1500... For $1500 you can buy a complete H22A which will make more power and be far more reliable.

If you wanted to build a "G23" to be able to handle the extra RPM's required to take advantage of the DOHC VTEC head, you are going to have to completely tear the bottom end down and rebuild using aftermarket "Race" bearings and other componants. A F23 bottom end was not designed to turn 8K+ rpm. By the time you pay a machine shop to do all the prep work to the block, install new bearings, install K20A pistons, you will have at least $600 in the bottom end alone, not even counting the price of the block. The H22A head is going to set you back about $400. Then (if you aren't a dumbass) you are going to want to have it prepped by a machine shop also (check tolerances, etc). Throw in a few hundred more dollars for all the other little shit involved, plus paying someone to assemble the engine, and now you are getting close to $1500.

JUST BUY A DAMN H22A. Think about it. How can a stock parts "G23" make more power than a H22A? Even if you use the K20A pistons in the G23 it will still only have close to the same compression ratio as a stock H22A. It's reall not worth the time and money. Buy a H22A, throw a set of cams in it, a good header, euro R intake mani, a good tune, and call it a day. That should put you over 200whp, and it will last forever if you take care of it.