Chosen Solution
Answering my own question: 1: I had to make up an extender from a standard 30 pin FFC (i chose Molex 0151660325 from Digi-Key) and a 40 pin extender adapter from Adafruit, #4523. If i had it to do over again i’d get a longer FFC, so it could twist and allow setting up the MBP in a normal orientation. 2: The key caps on the iFixIt IF161-121-1 pull straight off and snap on as for the original Apple keyboard. The space bar failed because the plastic tangs on the space bar key cap that hold one of its two long stiffening wires lost their ability to hold the wire in place. I wrote up a whole WWW article on my personal site, discussing all of this in-depth, in case anyone wants more information.
