Question on note-spacing

[Doug Asherman]

Hello:

I have what is probably a very simple question, but I can't seem to work 
it out. Below you can find the source for one bar from the Concierto De 
Aranjuez; if you compile it, you'll see that the eight note after the 
second group of 64th notes is a little close to the last 64th note. I 
was wondering if there was any way to fine-tune this a little.

Here's the excerpt

\version "2.1.25"
#(set-global-staff-size 26)
\header {
  title = "One bar from the Concierto De Aranjuez"
  composer = "J. Rodrigo"
}

melody = \notes \relative c' {
  \time 4/4
  \key d \major
    <<
    { \stemDown <g d' b'>4 }\\
    {
    \stemUp
    b''32-4[ a-2 b16-4 ~ b64 cis-4 b-2
    \set stemRightBeamCount = #2 a-1
    \set stemLeftBeamCount = #2 b-2 cis-4 b-2 a-1]
    \stemDown
    b8-2[ \grace { cis32-4[ b a] } b8] ~
    b16 \set stemRightBeamCount = #1 b-1
    \times 2/3 { \tupletUp \set stemLeftBeamCount = #1 b16 b cis }
    d64-2[ e-4 d e d16 \acciaccatura e
 d cis]
    }
    >>
}

\score {
  \context Staff \melody
  \paper { }
}

Thanks in advance for any help.

Doug