A direct pitch on top would work great. I've done it twice and one was my RIS (1.105), the other being a big Tripel. I've also done the wash thing for brews below 1.070.
I would try and rack off as much of the Irish red as possible, but I doubt you would get much flavor transfer to a big stout like you're planning.
Primary #1: Empty #2: Empty
Secondary #1: Blackberry Rhubarb wine #2: Empty #3: Empty
Kegged: Dusseldorf Altbier II
Bottles: Big 50 Barleywine, Framboise Lambic, Russian Imperial Stout, Barolo Wine, Berry Rhubarb Wine, Black Currant wine
On Deck: Border Crossing Vienna, BGSA, 2 Hearts IPA, Pumpkin Ale, RIS