I advise strongly against the 4 inch stroke in a stock cam ht 350 block.
If you are an experienced stroker engine builder and fully understand what to do and where and why to end up with the correct clearances and not grind into water or oil passages, you will have a lengthy time consuming chore on your hands.
If you aren't you are in for a learning experience which can eat up several days time and that is if you don't ruin the block while cutting.
Ed