In my continuing quest to test Kentmere 400 in 2020 I decided to try it in my favorite HC-110 dilution…dilution H (1:63). When trying new developing schemes my first step is to consult the Massive Dev Chart to see what they recommend. Unfortunate for me there were no times listed for Kentmere 400 pushed to 800 developed in HC-110 dilution H. Ugh. I then checked on filmdev.org, flickr, and even asked in photography groups on Facebook, but was still left with nothing. So, if someone had used this film/developer combo, no one was saying what they did. While I was somewhat disappointed, I was also excited to be, what I considered, blazing a new path.
Below are my results of shooting Kentmere 400 pushed one stop to 800 ISO and developed in HC-110 dilution h(1:63). My solution was just to double the Massive Dev recommended time for dilution b(1:31) and then adjust the time +30% for the one stop push. This gave me a time of 25 minutes. Agitation was done using the swizzle stick constant for the first 30 seconds and then 15 seconds every two minutes for the remaining development period. Stop bath, fix and wash were all standard times.
I must say that I am quite pleased with how this film/develop process turned out. Next may be trying this on a roll pushed 2 stops.
God Bless and Happy Shooting!
Negative Development 
I usually follow these guidelines per the recommendation on massive dev chart
http://www.digitaltruth.com/devchart.php?doc=pushproc
Standard Developer
1 stop push = (x1.5)
2 stop push = (x2.25)
3 stop push = (x4.5)
I think trying with 30% you were in the ballpark. I don’t know if your negatives were the proper density or were they a little thin. I can’t tell from the images, they look like they turned out good.