For pipe blends using pressure-fermented Perique, which is distinctly alkaline, it is blended with the acidic flue-cured Virginia. I've found that the final pH balances with about 3 parts Perique to 5 parts flue-cured Virginia (though this ratio varies with the strength of the Perique). If you consider those "parts" as ounces, then the Perique/Virginia blend makes up 1/2 pound. The other half pound can be the same, or can be 4 parts Oriental and 4 parts fire-cured (or Latakia). This produces a fairly convincing English pipe blend. But its edge at the tip of the tongue is produced by the flue-cured component.
Flue-cured Virginia ages very slowly, if at all. If the flue-cure regimen goes above 191ºF, as some do, then all the oxidizing enzymes are denatured, and the leaf will not age further.
Virginia (or other flue-cure classed variety) that is air-cured, then aged, is what the pipe tobacco world calls "mature Virginia," which is typically a reddish brown, and is fairly easy to make by just kilning your air-cured Virginia-type leaf, or allowing it to naturally age for a year or three.
Bob