Some folks have tried to give you real advice, that is being ignored by many (quick lock is only used on engineered floors- tongue and grove is only used on solid wood).
That aside- there are some other fatal flaws nobody mentions. Before wasting time, money and ruing good wood, consider this:
1) You don't even know if you floor can handle wood. Have you done a moisture test without the heat on? How about with the heat on? Some slabs will never get a wood floor if they have too much moisture.
2) You did not mention how you intend to mill this wood. Unstable woods (which hickory is one of) used in flooring must be quarter sawn. It will make the majority of the woods movement vertical, and not horizontal, preventing buckling and cracking. Do you know how to quarter saw? Do you have enough trees to produce enough quarter saw wood?
3) You don't mention how you intend to dry the wood. Are you aware all wood used for flooring needs to be kiln dried and then planed to size? Do you have a proper kiln? Can you get to 11-12% moisture content? If not, you will have a floor that is a complete mess.
4) Radiant heat directly under a solid wood floor can cause the flooring to dry out quickly and contract in size, causing cupping and/or large open gaps between the boards. Any quality shop who knows wood floors, will tell you they never put a solid "unstable" (hickory, cherry, maple & pine) over these systems. If they do, it is without any warranty, as they are all too unstable to not react. Hence the heavy recommendation and practice to use engineered over these systems and limit the temperature to below 80 degrees.
And when all else fails and one still considers doing this, contact some of the major manufacturers (large and small) and then visit some shops who specialize in hard wood floors. Ask them why they never came up with the idea of putting a "click lock" into solid wood- something that every installer would love to speed up installs. They will tell you that it won't work and failure is likely and they won't even make it. Then ask them if they would ever put solid hickory on a slab with a radiant heat system. Most if not all will tell you no- due to its instability.
You can do what you want- have hardwood over a slab. You just need the right wood, with the right install method. Solid self-milled solid hickory is not really an option if you want something that lasts more than a handful of years. Now if you want to make your own engineered version- it is a lot of work, but can be done and will work. It will also be more expensive than if you just bought it.
