For me in the development stage I would leave out the pre-wash and dump the stop stage and use water instead , use the developer at 1+14 at 20c and follow the times and Ifords agitation advice. I say this because I use the same chemicals in my development for HP5 and other modern 400 films and never had much of a problem with the results.I would also not fix for 8 minuets but maybe thats just me.
As for the paper printing did you get the same with a test print, I get good grade result even using home made rodinal for paper development and rarely ever go above grade 3.5 perhaps your filters are in the wrong envelopes try going through 5 test strips one for each grade to see the results.
What I have posted is what I would do in your situation.
Also add the bullet points in the post 25 from Mr Kotch..