.700 lift is not a wild cam by any means in a BBC. But what may be happening is that the heads don't flow well enough to make use of that cam would be my guess. So, I think that epitomizes grumpy's point of matching parts.
I went to the drags last night and a buddy of mine had his chevelle out. BBC 468, 4 bolt, steel crank,, roller cam, Dominator on alky, eagle rods, 13:1's. He had iron oval port heads, was running 12.10's to 12.30's in the quarter. He purchased some Brodix BB3 heads, slapped them on and his best time of the night was a 12.00, mostly 12.10's, so he didn't gain all that much, if any, with the rectangular port brodix heads. So a quick check with brodix and the BB3 cylinder head has a 370cc intake port and is designed for 555 to 632 cubic inch engines!!!!
Is it any WONDER that it didn't pick up any power??? No, probably not, his TQ went in the toilet and his HP did too!!! But being able to say you have BB3 heads is, well, worth what when you are bench racing? Not much in my book.