With a lake that big you really need a professional to come out and do a survey. Based on the numbers you gave I would say you are looking at $20,000 of fish that may not be needed. A $1500 electrofishing survey would help you determine if additional stocker fish are needed and if not the money can be used somewhere else where it would have a greater impact.
Dying a lake that size will first be expensive, and second will probably be ineffective. Do you have an idea of the flow rate that is leaving the lake? If you have a high flow rate out of the pond the dye will dissipate quickly and not do what it was designed to do.
With a lake that big you could try Crappie. They usually aren't recommended in small lakes because their spawning cycles are boom or bust and they have a tendency to stunt.
Liming will be ineffective in a spring fed lake because it will quickly be washed out in a similar fashion to the dye.
Fathead minnows will be better for a new lake or pond. They reproduce much quicker than mosquitofish.
