A67 blocks B77 below the waist and immediately A88 blocks
B77 high.

Is this considered a chop block in HS? How about NCAA?
This is considered a chop block in the NFL (only on pass
plays and on run plays away from the action).

NF Interpretation
 

No. Think of it this way. The high block is not illegal. It's the BBW while there's upper body contact, the actual chop block, that makes it illegal. The play that you described is perfectly.

Thanks for the response BktBallRef. I guess I was thinking
of it more in the terms of it being a player safety
violation as opposed to interpreting the exact language of
the definition.

How about in college?

With regards to your play, the player is no more at risk than any other legal BBW. In a chop block, the safety isue is that the defender is engaged by a blocker who is blocking high. He has no defense for the blocker who is about to hit him at the knees. That's the difference.

Don't know about college.

Take a look at the charts at this site:
http://www.atlantic.net/~gilbertr/b-30menu.htm

They'll give you a good idea of the NCAA definition
and ruling for chop blocks