goin BB
Big block K-members were only made in 67 - 68, are pricey when you can find them used, and from what I have read, don't work with all RB / B block castings. Direct Connection produced a big block K-member for a few years, but they are pretty scarce now and reportedly were not of the greatest quality when new. Another option is to modify a 73+ small block K-member. Sorry - don't mean to rain the gloom and doom on you, but I just went through this myself trying to figure out my path to a big block swap.
There's lot of good info on this page - definitely worth a read:
Tips, Tricks And Tight Spots
