A sleeved LS & CRV block, will have about the same structural strenght as a GSR, ITR or even a B16 block for that matter. The only advantage that the LS/CRV blocks would have is the ever so slightly higher 212mm deck height versus the 211.84mm of the GSR/ITR's. This really doesn't matter for 99.9% of the people who builds motors and do not play with custom rod and pistons pin heights. That, and the fact that you can get LS/CRV blocks cheaper.
Now the advantage of GSR/ITR blocks would be of course the main girdle. As for the oil squirters, some people see them as a disadvantage because of the oil pressure that they waste. A set of coated forged pistons will compensate for the lack of oil squirters. If you choose to run squirters just make sure to run a 94+ vtec oil pump as they have a higher pressure output to compensate for the oil squirters.

I wouldn't worry about knife edging the crank. As Scott said, Honda cranks do not sit in the oil as some others do. Knife edging requires the removal of material from the counterweights. Doing so...you will lose rotational mass...hense quicker spool up, but at the cost of torque. On a FI motor I wouldn't worry about this as once in boost...you'll find that the motor will spool up just fine
Other than this...the 87.2mm GSR/ITR, and 89mm LS/CRV cranks are all about the same when it comes to torque. Your numbers may slightly differ, but not by much.
The real different between the cranks is displacement. The more you increase stroke, the more displacement you make. The more displacement you can make, the more power. The problem is with every action...there is a reaction. In this case, the more you increase stroke, the more you increase piston speed. Increase piston speed compounded with higher RPM's can cause more interial forces which if not addressed, can and will in most cases cause rod failure. Other issuses like less TDC dwell time, decrease cylinder filling, and of course, cylinder side loading are all increased when increasing stroke. NOW BEFORE YOU START, NOWHERE DID I SAY THAT INCREASING STROKE IS BAD!!!
It's just one tool of many when trying to make power.

And finally, which head is better? It really depends on who you are and what you are doing to do to the head. As said earilier, the PR3 heads tends to slightly have more options available than the P72. This does not mean that it is better. I prefer virgin (never ported) PR3 heads. But I'm sure there's more than one person on here who will tell you different.
As far as heads go...I will say that with most engine...the ablity to flow air is the most important thing. There's a saying that "all the power is in the head" and it's true! So with, I would build the head and have it port by someone who has a good rep for porting...but more important...has a flow bench!


That's my rambling for the day.