Add 6ml x 5 of concentrate to a jug and fill it up to 1030ml. Process your film.
Those numbered dilutions (A, B, E, etc) were to try and provide some 'time uniformity' with some processing systems. You are correct in thinking that you cannot use dilution "E" because you tank is too small.
What he said - and you can use the dilution B times, because effectively that is the dilution you will be using
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
I recently carried out some testing with HC110 and my jobo cpp2 with 4x5 fomapan 400 and using my XRite 811 densitometer. I took a series of exposures at various isos from 400 down and rotary processed them in my cpp2 using HC110 with a concentration of 1+30 for me that was 600 mls distilled water plus 20 mls of HC110, after fixing and drying I tested them on my densitometer and the negative that gave the correct density gave me a exposure ISO of 250, I then carried out some further development trials with film exposed at ISO250 and discovered that the best processing time for the highlights was 5 mins and 45 seconds on the rotary processor. This will now be my n development time for that film in HC110. I haven't got around to doing the n- or n+ timings yet but i believe you can approximate these with +/- 10% of the n time.