How much cover do you have for your Sunfish/Fat Heads?
How much shore cover and how much underwater structure?

Do you have aqautic plant life? i.e. Lilie Pads, Cat tails...grass..etc..?

Also what is your goal? Instant bass fishery or hog pond? Large Bass or Plenty of Bass?
I personally would start with trying to create a hog pond.
Here is why, You can always create a "Plenty Pond" later. If you stock 10-15 Large bass and let them grow over a summer, First your bass will have very little competition for food, will grow faster and have a headstart over all new comers, this will insure you pond will have some good lunkers. Instead a pond of all 8-12 inch fish the first year then few 12-15 inch the next. You will have a pond with 10-15 (3-5lbs) lunkers the first then you could stock smaller bass (fingerlings) at the same time. I would use fingerlings because they wouldn't compete directly with the bass for forage until they get 8-12inches long.(except for the fatheads)
Also by the end of the summer they should be large enough to keep the spawn of the sunfish in check.

You also have to be careful as you could transport diseased fish this way but if it was me I would:

1. I would make sure there were some good cover for my smaller fish to hide and use.
2. Visually inspect any bass you plan on importing for any growths, sores or defects.
3. Transport the largest 5-15 bass over 3lbs to your pond.
By the end of the summer you should have some nice 4-5lb hogs. With no other predators and plenty to eat These fish would definitly work well in there.

Just my .02

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