I wonder how a blue and a buff became red? lol
Anyway, just my opinion. If you breed him to buffs then you lighten the red color. If it was me. I would try crosses Big Red's parents over and over until I got me a redish pullet. And then breed her to big red. Your more likey to get Red looking Orps.
Your well on the way to Red Orp. He is a beauty might I add.
*wink wink* I'm working of Chocolate Cochins soon. Maybe I will include some orpingtons too.
ETA: Oh. I skipped a few pages. I see that your breeding back his daughters, then back again until you get a red color. lol That will work too.
Best wishes for you to get red. I got some surprises in color in my mixes birds too. And I just can't seem to reproduce it. Darn the luck. lol