The /æ/ vowel is spelled <a> followed by two consonants or by one consonant in a monosyllable. The /əʊ/ diphthong has a variety of spellings including <o>, <oCe>, <ow> and <oa>.
This contrast is between a short vowel and a diphthong with the sounds well separated in the mouth, so it should not cause any problems.
There is one pair involving a mildly taboo word: fanny/phoney.
Interesting pairs include:
ashen ocean
bracken broken
elapse elopes
morass morose
pallor polar
passion potion
The density value is 4.19%. The pairs make 135 semantic contrasts, giving a loading of 50.2%.
abbey obi abbeys obis Abo oboe Abos oboes ad ode ads odes add ode adds odes adder odour adders odours am ohm and owned Ann own anna owner annas owners apple opal apples opals as O's ashen ocean at oat ax oaks bad bode baggy bogey ban bone banned boned banners boners banning boning banner boner banners boners bast boast bat boat bats boats batted boated batting boating batman boatman batter boater batters boaters black bloke blacks blokes bracken broken brag brogue brags brogues brasher brochure cabby Kobe cad code cads codes Calor cola cam comb cams combs can cone canned coned canning coning cans cones Cannes Colne canny coney cap cope capped coped capping coping caps copes Capt coped cat coat cats coats catch coach catches coaches catching coaching Chas chose clack cloak clacked cloaked clacking cloaking clacks cloaks clan clone clans clones crack croak cracked croaked cracking croaking cracks croaks cram chrome crammer Cromer cranny crony crannies cronies dam dome dams domes damn dome dammed domed damns domes drag drogue drags drogues elapse elopes fan phone fanned phoned fanning phoning fans phones fanny phoney fannies phoneys flan flown flat float flats floats gad goad gadded goaded gadding goading gads goads gaffer gopher gaffers gophers gal goal gals goals galley goalie galleys goalies gash gauche gassed ghost GATT goat glad glowed gnat mote gnats notes grand groaned hacks hoax had hoed Hal hole Halle holy ham home hammed homed hamming homing hams homes hap hope happed hoped happing hoping haps hopes hapless hopeless haplesslessly hopelessly has hoes have Hove jab Job jabs Jobs Jack joke jacked joked jacking joking jacks jokes Jan Joan knap nope lab lobe labs lobes lad load lads loads ladder loader ladders loaders lam loam land loaned lap lope lapped loped lapping loping laps lopes lavs loaves mac moke mad mode man moan manned moaned manning moaning mans moans map mope mapped moped mapping moping maps mopes massed most mat moat mats moats matted moated matter motor mattered motored mattering motoring matters motors Max mokes morass morose nap nope Nat note national notional pack poke packed poked packing poking packs pokes packer poker packers pokers pal pole palled poled palling poling pals poles pal poll palled polled palling polling pals polls pallor polar pan pone pans pones pap Pope passion potion passions potions pastel postal patch poach patched poached patches poaches patching poaching rag rogue rags rogues ram roam rammed roamed ramming roaming rams roams ram Rome rap rope rapped roped rapping roping raps ropes rat rote ratch roach ratches roaches ratter rotor ratters rotas sad sewed sally solely salon Solon sap soap sapped soaped sapping soaping saps soaps sappy soapy sappier soapier sappiest soapiest shad shewed shall shoal slap slope slapped sloped slapping sloping slaps slopes smack smoke smacked smoked smacking smoking smacks smokes smacker smoker smackers smokers stack stoke stacked stoked stacking stoking stacks stokes Stan stone stand stoned tabby Toby tack toque tacks toques tan tone tanned toned tanning toning tans tones tap tope tapped toped tapping toping taps topes tat tote tatted toted tatting toting tats totes tattle total tattled totalled tattles totals trap trope traps tropes vat vote vats votes whack woke yak yoke yaks yokes
John Higgins, Shaftesbury, November 2009