Initial capex is put US$67 million for a five-year operation producing an average of 78,000 ounces per annum at all-in costs of $915 per ounce after tax.
Using a gold price of $1400 per ounce shows an after tax net present value of $122 million and internal rate of return of 51%.
Tuvatu has indicated resources of 1 million tonnes grading 8.5 grams per tonne for 274,600oz and inferred resources of 1.3Mt at 9gpt for 384,000oz.
Lion One believes there is "exciting exploration upside", with a hit of 87.5gpt over 3.3m reported from drilling below the Tuvatu resource earlier this month.
The ASX and TSX-listed Lion One recently raised C$35 million by issuing new shares at $1.70 each.
Shares in Lion closed at A$2 Monday, capitalising the company at $272 million.