Priobe
Yes you can shave the heads as that is what I did to mine but one change always requires other checks such as: Piston to valve clearance, piston to deck clearance, intake to head ports (heads drop then so do the ports), etc. I still think it is worth it and with your combination I would go a full point to 10.5:1. It would be pump gas friendly and really help the Webers sing!
When reducing the combution chambers a point can be made by reducing the size by 7 cc - I believe - someone correct me if I'm wrong.
At the rate were going we might, with changes, get you up to the high 400's!
Like Exc.... said before 450 hp is plenty that's why he has 675
but with the awe factor of Webers it feels like 650hp on visual appeal alone - it's the cat's meow!