Hi WadeB,
Unfortunately … there are too many unknowns, variables, and personal preferences involved for anyone to know how any specific design may feel for someone else based on specs (either yours or a mattress) or “theory at a distance” (see mattress firmness/comfort levels in post #2 here).
If you are planning to design and build your own mattress then I would also make sure you’ve read post #15 here and the posts it links to in option 3 just to make sure you have realistic expectations about building your own mattress and are prepared for some of the trial and error that may be involved. The best approach with a DIY mattress is to to approach it with a “spirit of adventure” where the process itself and what you learn along the way is more important than any cost savings you may (or may not) realize.
Have you tested a mattress with the same or very similar specs that you are using as a reference?
Post #4 here includes the better sources I’m aware of for mattress components … including covers.
Phoenix