As proposed, I am using a combination of CV, (V)C and diacritic symbols, plus a few lexemic symbols.  I will use a semi-orthographic rendering of the symbols:
 
Base CV symbols:
  '  p'  t'  k'  f'  th'  s'  h'  m'  n'
  a  pa  ta  ka  fa  tha  sa  ha  ma  na
  a' pa' ta' ka' fa' tha' sa' ha' ma' na'
  e  pe  te  ke  fe  the  se  he  me  ne
  i  pi  ti  ki  fi  thi  si  he  mi  ni
  o  po  to  ko  fo  tho  so  ho  mo  no
  u  pu  tu  ku  fu  thu  su  hu  mu  nu
  u' pu' tu' ku' fu' thu' su' hu' mu' nu'
 
Base VC symbols:
    p  t  ch  k  f  th  s  sh  n  m  ng  l
 i ip it ich ik if ith is ish in im ing il
 u up ut uch uk uf uth us ush un um ung ul
 r rp rt rch rk rf rth rs rsh rn rm rng rl
 
Basic diacritics:
  +voice, applies to both CV and VC (*)
  +pre-sibilant, applies to CV only (_s)
  +pre-nasal, applies to VC only (_n)
  +rhotic glide, applies to CV only (^r)
  +lateral glide, applies to CV only (^l)
  +palatal glide, applies to CV only (^y)
  +labiovelar glide, applies to CV only (^w)
 
The palatal glide is also a palatization diacritic for the alveolar series:
  ta^y = cha; sa^y = sha
 
We have 80+51 base symbols + 7 diacritics: 138 symbols.
 
Probably some extra symbols for the -ed and -(e)s semi-lexemes.
 
Now, on pronunciation of vowels for American English
  C'   schwa.
  Ca   as in "fat": fa+t
  Ca'  as in "father": fa',th'*+r 
  Ce   as in "pet": pe+t
  Ci   as in "pick": pi+k
  Co   as in "pop": po+p
  Cu   as in "cut": ku+t
  Cu'  as in "put": pu'+t
 
Pronunciation when followed by iC:
  Ca iC   as in "fate": fa+it
  Ca'iC   as in "pike": pa'+it
  Ce iC   as in "Pete": pe+it
  Co iC   as in "boy": po*+i
 
Pronunciation when followed by uC:
  Co uC   as in "Pope": po+up
  Cu uC   as in "dude": tu*+ut*
 
Pronunciation when followed by rC:
  C' rC   as second vowel in "father": fa',th'*+r
  Co rC   as in "cork": ko+rk
  Cu rC   as in "fur": fu+r
 
Most of these values apply to British English as well, but then CV+rC is rather a mark of lenthening:
  Ce rC   as in "fear": fe+r
  Ci rC   as in "here": hi+r
  Co rC  as in "for": fo+r
etc.
 
This would represent a few difference between dialects, but most dialects would follow the above examples.
 
This script might be reduced even more.  For example we can reduce the set of valid vowels in CV syllables to five or four, and have a diacritic to slightly shift the value of the vowel; or the set of basic consonants by taking together the respective stop and fricative in the same point of articulation:
 
  ?A PA TA CHA KA MA NA
  ?E PE TE CHE KE ME NE
  ?O PO TO CHO KO MO NO
  ?U PU TU CHU KU MO NO
 
Then: P for /p/,   P* for /b/,   P# for /f/  and P#* for /v/
      T for /t/,   T* for /d/,   T# for /T/  and T#* for /D/
      CH for /tS/, CH* for /dZ/, CH# for /S/ and CH#* for /Z/
      K for /k/,   K* for /g/
      ? for /?/ or null,         ?# for /h/
 
And the vowels:
  A for /&/, A! for /I/ (former Ca and Ci)
  E for /@/, E! for /E/ (former C' and Ce)
  O for /a/, O! for /A/ (former Co and Ca')
  U for /V/, U! for /U/ (former Cu and Cu')
 
Then, the same glide diacritics would apply, and
  ?_s for /s/, ?^r for /r/, ?^l for /l/, ?^y for /j/, ?^w for /w/
  ?*_s for /z/, ?#^w for /hw/
 
For the offsets (VC) we have:
    -P -T -CH -K -M -N -NG -L
  Y YP YT YCH YK YM YN YNG YL
  W WP WT WCH WK WM WN WNG WL
  R RP RT RCH RK RM RN RNG RL
 
Plus the fricative and voicing diacritics.
 
This gives 28+35 symbols, plus 8 diacritics: 57 symbols.
 
-- Carlos Th