The most recent advice you have received on bullet diameter would have you operating at (or slightly under) bore diameter...after patching. In order for a bullet of that size to bump up enough to seal the bore, it will probably need to be somewhat 'soft'. Wheelweights may not give you what you need.
On the other hand, a 'fatter' bullet patched to groove diameter will require less bump. So, it's something to consider...
CM