An option that can be considered is to sell the base metals to a...

An option that can be considered is to sell the base metals to a streaming company. It is all number balancing, and does add to an already pretty complex circuit, but the upfront funds could potentially cover the additional costs of the base metals recovery circuit and possibly cut in a little to covering capex for the rest of the project.
We don't have enough info as yet to calculate even roughly, but they don't seem to be a haphazard crew, so must see real potential to be exploring this avenue further.