That's a P/E calc. The idea behind my wanting to do a NAV (Net Asset Value) calc is that valuing a gold company by P/E (or by in situ) is specious: it assumes production can continue indefinitely (but all mines have a lifespan), it doesn't incorporate time value of money (future production shouldn't be valued at today's dollars), it assumes a constant price for a resource, it doesn't incorporate risk, and so on. The professionals do NAV calcs.

Also, and this also may apply to your style of calc, I suspect that the reason CMM is "undervalued" right now is that the market isn't giving them credit for any more than they've already accomplished. Like, what happens if you run your own calc at only 400 tpd and 3g/t gold at $570 cash cost? Lamaque's value per share is then 29 cents. That would suggest that CMM's price will increase by $1.55 if they meet your 65000/y target.

Your calc does work out to a logical solution in this case, but a NAV calc should work as a higher-order confirmation.