How much power can the stock block safely handle? I would consider both N/A, and a supercharged application if that makes a difference. I was hoping to make in the realm of 450-500fwhp, but am considering a supercharger to maybe make 550-600fwhp. Thank you for any information.
There is no set number. Most feel that 400-500 is it. Some have gone way over with a stock block and not split it. In my opinion, rpms make a difference as well as if you are putting a blower on. The rpms for obvious reasons and the blower because of front loading the crank. To get to 450-500 hp on a streetable motor, you are pretty much going to have to go the power adder route.
Do you plan on using a stock bottom end, or are you going to put together a stroker?
The figure 500rwhp has been banded around but I know of some stock blocks still living with a little over that while I've also heard of blocks splitting with less.
Avoiding detonation and properly balancing the bottom end are probably the key to a longer block life.
I've gone over 500rwhp for a while. I've never been worried about it. Put a girdle on the bottom end so if you do split it the block atleast stays together.
Building it right can give you a little extra insurance. The Mexican blocks are said to be good up to 700 HP, due to the higher Ni content, but that is up to you.
Bottom line: if you feel that you're close enough to ask, you are already past it.
If you are thinking of nitrous, turbo, or blower with a stroker, just go Dart now, and have the piece of mind. If just a NA stroker, keep stock. Now, if you are going to be turning 6500 RPM with 11:1 or higher CR I'd go dart NOW.