Tex,
I am not making a case for big bores on the bench, they are not bench guns we never designed to be. A small pillow in your shoulder helps, if you don't have a gel pad.
Even in the field I like the extra 1/2 lb or so. With this class of rifle balance is important, and when they get light they don't have that balance. I am not suggesting a field piece here, but some of these rifles are right at 8 lbs and I want the extra weight, when it is done right this is mostly in the larger contour of the barrel, and the extended magazine, with a good weigth distribution.
Around 10-10.5 ( max 11 ) is ideal, in my mind, my reference is to above the 375 H&H caliber here, the 416/424/458 calibers have a lot more recoil.
Back to the CZ 550, even with the American stock these need some help. I have done a fair amount of reading on these, and in the 416 Rigby these are going as little as 10 shots and cracking the stock. If you start with the American stock, these can be doctored by adding crossbolts (if it is a Lux stock I wouldn't bother), depending on how handy you are this can be a fairly low dollar upgrade, or cost a fair amount if you have someone else do it.
My CZ 550 is in 6.5x55 so it doesn't have anywhere near the recoil of the big bores so I am not nor do I suspect I will have issues. The going rumor is if your CZ is chambered above the 375 H&H, do stock work first. Here is a link that goes into the hows and whys much better than I will:
http://www.accuratereloading.com/ub...umber=370556&page=&view=&sb=5&o=&fpart=1&vc=1
My suggestion on a new stock has justification in that when you are doing stock work, the labor costs the same whether you start with a plank out of the barn or a good stock blank, nothing changes in the amount of steps needed to make a stock. A couple of hundred dollars spent on a good piece of wood makes the difference between having something nice and a reworked barn door on your rifle.
CZ is also talking about introducing the 505 Gibbs next year, don't hold your breath, but it has been talked about and requested several times. One thing I really wish CZ would offer is an option to buy a better grade of wood on these, a good straight grain English walnut would be nice. They could finish it like they are now, but this would definately be a nice option, and make the work on their stocks worth the effort. This shouldn't be more than a $100-150 upgrade, and I would jump on another CZ with that option. Their is some cryptic reference to it on their website but none of the dealers know anything about it.