The /ʃ/ sound is spelled only with <sh> in this set. The /ŋ/ sound is spelled with <ng>.
This is a contrast between a voiceless alveolar fricative and a voiced velar nasal continuant. It is not a problem.
The contrast can only occur finally. Many pairs arise from contrasting an adjective ending in -ish with a related verbal -ing form such as bookish/booking. Other interesting pairs include:
The mean density value is 0.9%. The list makes 78 semantic distinctions, a loading of 91%.
apish aping babyish babying banish banning bash bang bashing banging bashed banged bearish baring bearish bearing blackish blacking bluish bluing bookish booking boyish buoying brandish branding brownish browning brutish bruiting burnish burning clash clang clashing clanging clashed clanged clownish clowning dampish damping Danish deigning devilish devilling donnish donning dwarfish dwarfing fairish faring fattish fatting flush flung foolish fooling freakish freaking gash gang gashing ganging gibberish gibbering gosh gong greyish graying hash hang hashing hanging hoggish hogging huffish huffing hush hung longish longing lumpish lumping lush lung mannish manning Moorish mooring offish offing palish paling peckish pecking peevish peeving pettish petting piggish pigging pinkish pinking Polish polling punish punning rakish raking rash rang reddish Reading Romish roaming roughish roughing roundish rounding rubbish rubbing rush rung sash sang shortish shorting sickish sicking slash slang slashing slanging slavish slaving sluggish slugging slush slung snappish snapping Spanish spanning starfish staffing steepish steeping stylish styling swish swing swishing swinging thievish thieving ticklish tickling uppish upping waggish wagging whitish whiting wish wing wishing winging wolfish wolfing yellowish yellowing
John Higgins, Shaftesbury, December 2010.