Since you have to rebuild the engine anyway, I might suggest something else that will greatly increase combustion efficiency. They're called "Singh Grooves" and can be found at
www.somender-singh.com. It's really easy to implement (once you have the heads removed) and will add only an hour or so of extra work. The results will be anywhere from "definately didn't help, can feel a little more power" to "OMG WTF did they give me a big block??"
Their biggest advantage is at low RPM, but has absolutely no high-rpm sacrafice. There have been race engines that are cammed up to the point that they won't idle below 1800rpm before the grooves, but after they're grooved they will idle smooth at 600 rpm. It greatly speeds up the initial flame front and makes the A/F mixture burn much more quickly overall. The result is less pinging, and allows for higher CR. Experiments have been run on NA engines that pinged on 87 octane gas at "stock" settings but with the grooves were upped in compression but refused to ping on the same fuel.
Also, since the mixture is burned so much more quickly, the engine temperature is greatly decreased (and thus thermal efficiency is increased). Thus far, after a lot of experimenting, there have been no drawbacks found whatsoever. You may want to look into it.
I know this is "off topic" from the hydroxy injection, but I think they could be combined to create some extremely efficient engines.
A few websites that may be of some interest:
www.somender-singh.com
www.mpgresearch.com <-- Got hacked recently and is down temporarily
www.fueleconomytips.com <-- Also was hacked and is down temporarily
The last two were hacked due to "breakthroughs" that were being made in engine efficiency. Someone doesn't want that info to get out.