I read the meassage wrong, or I didnt read the entire message,
The 5-PW you could just soft step as described BUT the trim the 4 to an AW is not the ing to do when using taper tipped shafts. You could trim the tip to get the proper flex but you would have removed the "taper " part of the tip it the trimming process.
If the shafts come in 370 typically that are same length when delivered and then yes the trimming will work but check for total length juuuussst to make sure you will have enough shaft.
If the shafts are ordered from KBS and they are all the same length chance are the shaft is 370.
very few companies make a predetermined length in 370.
You may want to ensure the hosel they are going into is 370 not 355.
The best way to tell is using a micrometer or a gauge.