Don't get caught up in the premise that adding a bigger engine to an existing airframe will make you go faster.
Look at what this model is doing with a .40 cu/in engine.
http://www.youtube.com/watch?v=MM3nL4KdEqA
The QSRA planes are giant scale and do require massive engines with massive HP but the engine must be matched to the airframe in unison and proportionately or you will gain nothing.
The Diamond Dust and Shrike are not being manufactured any more but they are out there if you look for them. That is why it is very important for us speed flyers to have a stash!
Heck the whole Lanier line is gone now. I damn near cried when they closed up.
The Lanier 'Predator II" ARF was a fine speed plane also.
SPEEDY
Rev'ver Bro #184 ( I think!)
"Speed Freak"