Hi eges,
Welcome to the Mattress Forum! 
While I can certainly help with “how” to choose, it’s not possible for myself or anyone else on the forum to make specific suggestions or recommendations for combinations of materials or components that may or may not be appropriate for you, because the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress, and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort”, firmness, or PPP or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress), sleeping positions, health conditions, or “theory at a distance” that can possibly be more reliable than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
As you are attracted to the idea of designing and building your own DIY mattress out of separate components that are purchased from one or several different sources, then the first place I would start is by reading option 3 in post #15 here and the posts it links to (and option #1 and #2 as well) so that you have more realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project … the best approach to a DIY mattress is a “spirit of adventure” where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).
If you want to learn a little more, there is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel” that may help you.
You’re certainly looking at high quality and durable materials, and you’re considering a “traditional” progressive style of configuration. As to whether they would be appropriate for you, that can only be determined through your own careful personal testing. While your configuration would certainly lean toward a more “plush” configuration, I personally wouldn’t consider it an “overboard” plush configuration, but again your opinion would be the most important.
I’ll be interested in learning about any choices you make and the results of your personal testing, and an questions you might come up with after that.
Phoenix