Unless you are wanting the actual manual, you may be able to get by with the information in this link. Comparing it with my 1013A, the only difference I can see is the way the fuses are mounted.

http://www.repeater-builder.com/helper/helper-ind-sinadder-1.pdf


Don

Or maybe I should say an exact multiple of 12.5 khz.

Because 452.5khz is not an even multiple of 12.5khz.

It is my understanding that aviation was scheduled to change over to FM along with the other radio services. At that time private planes out numbered commercial planes several thousand to one so most of the expense would fall on hobby fliers. Many complained that they could not afford new radios and rather than have a lot of planes flying around with no radio, the FCC relented and dropped the change.
As for capture effect, it barely exist at 5khz deviation.  If capture effect was such a safety consideration, why did police, fire or any other radio service where a radio transmission could mean life or death change to FM. I don't think capture effect was even a considration at the time.