Hi bobfrog12,
If you have checked with the manufacturers and retailers on the Louisville list and none of them carry any “all latex” mattresses (some of them say that they carry Pure Latex Bliss which are all latex but their sites may be out of date) then there may not be any in your area. I checked the Pure Latex Bliss retail store finder for Louisville and it says that Louisville Mattress also carries their mattresses although they don’t say anything about the mattresses they carry on their website but they may be worth calling to check as well. If there are no all latex mattresses in your area then the only way to purchase one would be with an online purchase.
While I don’t have any specific suggestions because there are too many unknowns and individual variables that are involved with choosing a topper (including the type and firmness of the mattress underneath it which can also affect the thickness and firmness of a topper that works best for any particular person) … there is more information about choosing a topper in post #2 here and the topper guidelines it links to that can help you use your sleeping experience as a reference point and guideline to help you choose the type, thickness, and firmness for a topper that has the least possible risk and the best chance for success. It also includes a link to a list of some of the better online sources for toppers I’m aware of as well.
The choice between different types and blends of latex would be a preference and budget choice rather than a “better/worse” choice so it would depend on which type of latex you prefer. There is more about the different types and blends of latex in post #6 here and there is also more about the differences between Talalay and Dunlop in post #7 here that can help you decide between them although the most reliable way to choose would be based on your own personal experience.
This would be somewhat subjective and different people would probably have different opinions about how they would compare. In general the ILD ratings for different types and blends of latex aren’t directly comparable but if two manufacturers use the same methods of testing ILD (which they often don’t … see post #6 here) and if the ILD’s are accurate then for most people they would be reasonably comparable in terms of firmness although they will be different in terms of how they “feel”.
Phoenix