I'm not an expert either and to be perfectly honest, there are so many regional English accents the pronunciation for a word like book is different depending on which side of Liverpool you're on... so it's actually misleading of me in the first place to group the entire North-East together. There's a distinct accent in each of Durham, Newcastle, Sunderland and Middlesbrough - four major places in the North-East. People from Sunderland for example are known as Mackems and as the others around 'em like to point out, that's because they mackem and tackem (make 'em and take 'em).

Now, as for buck/book and lush/whoosh I think it also depends on how you pronounce those comparison words (ie, buck and whoosh) to determine what it sounds like. I suspect the way I pronounce whoosh convinced me it rhymed with the North-Eastern lush, but maybe you pronounced it slightly different (ie, like buck)?