Guitar expert George Gruhn
(of Gruhn Guitars in Nashville)
clearly states in his authoritative book
"Acoustic Guitars and Other Fretted Instruments: A Photographic History"
that a 1927 Martin 0-28K has:
1. a flat fretboard
2. a straight bridge saddle
3. frets ground flush with the fretboard
This guitar, however,
came from the factory with:
...a radiused fretboard and regular, raised bar frets...
...and a slanted (compensated) saddle.
Finally, let's look at
the serial number:
#27348 places it squarely in 1926.
In fact, according to Martin records, the last serial number for a 1926 guitar was 28689.
If one looks at the serial
numbers for 1926 (ranging from 24116 to 28689)
one would assume that #27348 is guitar number 3,232 of the total 4,573 made that year,
thus dates from approximately September of 1926.
We know, however, that
this guitar was not completed until February of 1927.
This indicates that Martin serial numbers refer to the date
the batch of guitars was begun, not when they were completed.