Yeah mate, you'll be right. Thrashing or not, if its going to break, it'll break. if you do decide on running the 3k bigport, in my opinion, piss off the old valve's, valve guides and seats and replace them with a 4k setup, far better oil seal setup. When i got my bp head reco'd they modified and shortened the guides for better flow, maybe that could be something else to look at,
cheers phatke30!