Turbodriz: You might want to do a little studying into water/methanol injection as it will greatly help in controlling detonation when your running pressures that high. Here are a couple of sites with some info, but I would recommend using Google and researching a little deeper.
http://www.sdsefi.com/techocta.htm
http://www.snowperformance.net/faq.asp
Also, pushing a 9.1:1 or 9.5:1 at low to mid 30 PSI WILL be pushing the 7M to the limit. To be able to build a motor that can run at the limit will require a great deal of research, tuning, time, and money. And more importantly experience. Fall short on any of these and the motor will die gloriously. Because the motor is run so close to the edge, there is no room for error, no buffer zone, the engine cannot tolerate it.
It’s true our motors don’t like to rev. Do you know why this is? It has to do with the very long stroke; it raises the piston speed to dizzying heights causing a great deal of stress on the internals. Building up the head helps airflow at higher speeds, but does nothing to deal with the initial problem, piston speeds. Read this for a little more info.
http://www.supramania.com/forums/showpost.php?p=180719&postcount=18
As for the cast iron block, yes, ours is cast iron, but so is the JZ. Both the JZ series and M series motors are aluminum head iron block. However the JZ series motors have a shorter stroke and are therefore more rev happy, this allows them to reach high horse power numbers easier. And the heads come designed to take advantage of the higher revs.
The JZ series motors are just more technologically advanced, they studied the flaws of the 7M and built a better motor. Toyota realized the long stroke wasn’t good for durability in a sports car, where people tend to rev it. So they shortened the stroke. Toyota realized they placed the cylinders too close together, so the moved them farther apart on the JZ blocks.
I’ve only heard of one instance where a guy hit 900hp on stock 2JZ internals, 600hp is considered the norm. 500hp is achievable on a 7M motor that doesn’t have 20 years and 200,000 miles on it
You mentioned iron blocks being able to handle a lot of abuse. Yes this is true, however on the 7M the cylinders are placed very close together, closer than most blocks. This causes the head gasket to be very thin where the cylinders meet. This is the weak link if you were to run high compression at 30+ PSI. The second the motor detonates at those pressure levels it will punch right through the head gasket. No leeway for error, no second chance. Your tuning MUST be perfect. Can you guarantee this?
I’m not saying that the road you want to take is impossible but, you will have to do a lot of research, you can’t just slap the motor together with over night parts from Japan, and expect it to work. You have to have the right parts and those parts must be set to the right tolerances. It will also be expensive to do it right. If you understand and are ready for those things then more power to you.
Also, listen to what IJ has to say, you don’t have to agree with him but at least hear what he has to say and consider it. IJ has spent more time pushing the limits of the 7M than most people here could ever dream of. As well as the limits of many other motors. The things he tells you come from experience, and you could learn a lot from him. He is not going to purposefully miss lead you, or intentionally give you incorrect information. Listen to his words of advice, he is here to help.