radar -
Your calculations seem reasonable and the share dilution seems reasonable (on the surface). Obviously, the debt holder expects far greater returns by getting the shares (at a discount to the current price with an anticipation of an increase in share price) than just getting (ever depreciating) cash.
I hate to see any share dilution but it wil be worth it if management uses the capital that they saved (by paying of the debt early) to reinvest in the expansion of GPR's current operations. That would expand output (and maybe even discovery activities) and hopefully raise the share price in a manner that may more than offset the "loss" of value from the new shares that are bring issued.
These guys seem pretty sharp and I hope that is how they are thinking.
- Panamax