Whoa, that's a radical recipe alright.
Most sources suggest 15% biscuit malt max. 65% Biscuit malt seems radical and, to me at least, a bit crazy.
I suspect there's nowhere near enough enzymes in 6lbs of pale ale malt to convert all the starch. Heck, it probably wouldn't even be enough with regular 2 row, let alone pale ale malt which has lower enzymatic power. If it was going to work, a protein rest might have helped, too.
That bitterness I suspect is the toastiness/biscuitness to an extreme level.
Radical is sometimes genius, sometimes crazy, but you've gotta try it it to figure which it is I guess. I give you props for trying it out.
Currently On Draft: Bamberger Rauch Dunkel, Belgian Blond, Pilsener Urquell clone, Smoked Porter
Bottled: Concord Pyment, Mi'Apa Sparkling Mead, Chimay Blue, Old Simcoe American Barleywine, Old Cantankerous
Fermenting and Conditioning: Pseudo-Decoction Munich Dunkel, Left Hook Bitter
Recently Kicked Kegs: Fresh Hop Pale Ale, Citra Rye IPA
On Deck: Old Rasputin, Northstar IPA, Ur-bock Dunkel