Check out this site for HC110 information.

http://www.covingtoninnovations.com/hc110/

You might want to look into some of the other dilutions. I am trying Dilution H (unofficial-not described in Kodak Pubs) with is 1:63 (about 1/2 strength of Dil B)
The development times for Dilution H are about twice the Dilution B times.

I use Tmax and it gives me longer times so I can do (N-1 N-2) without going with too short a development time.

The Massive Development chart says 5 mins for HP5 @400 with HC110 B.

http://www.digitaltruth.com/devchart.html

I hope this helps, it helped me quite a bit.

Regards,
John