I think 250whp is doable. There are already some post suggesting that a little head work opens things up nicely for higher revs, although that has been on FI applications so far. I wouldn't bother with power blocks tho as they will move the torque lower in the rev band which isn't what you want here.
I think at this point in the FA20s development the cams and intake manifold will be the most expensive and hardest to track down and they won't be off the shelf items.
I will be watching where this goes
