If you want to use the full power of vim then you can pipe output into vim.
$ ./ascript.sh | vim -
The output will appear in vim and you can use the full power of vim to do what you will. To select a block as you say above, you can move to a corner of your block of numbers and do Ctrl+V to start "visual block mode". Select the block, and then to copy it to the X clipboard you can do
"*p to copy to the X11 clipboard - use the middle mouse button to paste elsewhere
"+p to copy to the standard clipboard - use Ctrl+V to paste elsewhere
Of course if it is a one time command that is already on the terminal then this isn't an option, but I've found these techniques useful along the way, so hopefully other readers of this question also will.