/6 K-Frame vs. V8 K

The one I'm looking at is a SB 68 biscuit mount K. ID is not a problem, but does it make sense to get a Small block V8 K and have to put in mounts to convert to a BB instead of using original /6 k and adding BB mounts to it? I'm asking if the /6 is in any way less up to the job than the SB 8? Should I look for the V8 or am i wasting my time because the mounts will be similarly priced and there is little diff between the 6 and 8 strengthwise/structurally? Dont want to be ready to drop the motor in and find /6 K has to be hacked all over to make 383 fit. Thanks for all of the pics BTW!