Hi jack ate,
The quality of the materials is certainly good but there are too many unknowns for anyone to be able say how suitable it will be for your specific needs and preferences in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) based on “theory at a distance”. There are some links to some of the “theory” in mattress firmness/comfort levels in post #2 here but these are only generic guidelines and not specific to any individual person and the only way to know how a mattress will feel and perform for any specific person is their own personal experience.
If you have tested a mattress with the same or very similar specs and design at a local store and it worked well for you and the foams you purchased and the cover of your mattress are similar to the foam and cover in the mattress you tested then your odds of success would be quite high.
There are some sources for covers in post #4 here and for a memory foam mattress then a stretch knit cover that has the least possible effect on the memory foam would probably be the most suitable choice although there are some people who prefer a cover quilted with polyfoam with a memory foam mattress because it can create a more resilient sleeping surface for those who don’t like the feel of sleeping “in” their mattress as much (which is a “feel” that is typical of higher density memory foams that are usually more temperature sensitive).
As a general comment your support core is firmer than average and you only have 3" of memory foam and most 5 lb memory foam will feel firmer than lower density memory foam for most people so it seems to me that your mattress would certainly be in the “firm” range both in terms of comfort and support.
Phoenix