Hi roger -same experience here with the Nikon d800
As others have said you really need a modded dslr. Funny thing is that there's plenty of other dso's with dominantly h-alpha emission that turned out fine with the D800, but I've never managed to get a red tarantula without using a mono CCD and lrgb filters.
The LAB processed version you've produced is pretty damn good.
With a 180mm
http://www.astrobin.com/full/62545/B/
Through the tak FSQ and the best I could get was a sort of dried blood tinge.
http://www.astrobin.com/27741/
Cheers,
Andrew.