Installation Update . . .
I got the extension bracket aligned with the different (0.45") spacers. As such, I drilled the 'pilot' holes and put the 'installation guide pins' in at the 4 corners of the extension bracket. They will need a little bit of play in order to align with the matching holes in the transom.
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Now with these pins/bolts I can install the extension bracket without worrying (too much) about the alignment.
The sun was getting low on the horizon, so no time to bond the spacers to the E-B. That will be for tomorrow (sunshine permitting.)
I'll do an installation practice, check the alignment, and then drill the rest of the bolt holes. I ran a test of the 'open time' on the putty @ 60˚F and 2% MEKP. It stayed open for at least an hour and was showing signs of hardening at 90 minutes.
So, that will be my target . . . get the extension bracket installed and reasonably fastened within an hour of activating the putty.