/A/ versus /3/: 127 pairs

ah ugh
arc irk
arcs irks
argent urgent
argot ergo
arse Erse 
baa'd bird
baas burrs
bar bur
barbel burble
barbels burbles
bark burke
barked burked
Barking burking
barks burkes
barley Burley 
barns burns
Bart Bert 
bath berth
bathed berthed
bathing berthing
baths berths
Bern barn
Cali curly
calve curve
calved curved
calves curves
calving curving
car cur
card curd
cards curds
Carl curl
carnal Colonel
cars curs
cart curt
carton curtain
cartons curtains
cast cursed
Charles churls
dark dirk
darted dirtied
derbies derbies
far fir
farm firm
farmed firmed
farmer firmer
farming firming
farms firms
farthest furthest
fast first
fasts firsts
father further
fathered furthered
fathering furthering
fathers furthers
gargle gurgle
gargled gurgled
gargles gurgles
gargling gurgling
guard gird 
guarded girded 
guarding girding 
guards girds 
hard heard
hearts hertz
lakh lurk
lakhs lurks
larch lurch
larches lurches
larked lurked
larking lurking
Larne learn
larned learned
larning learning
larns learns
Mach murk
mar myrrh
Marge merge
palm perm
palmed permed
palming perming
palms perms
par per
parched perched
parches perches
parching perching
park perk
parked perked
parking perking
parks perks
parky perky
parley pearly
parrs purrs
parson person
parsonage personage
parsonages personages
parsons persons
partly pertly
pass purse
passed pursed
passes purses
passing pursing
Persia pasha
quark quirk
quarks quirks
R err
R's errs
scarf scurf
shark shirk
sharks shirks
spar spur
sparred spurred
sparring spurring
spars spurs
star stir
starling Stirling 
starred stirred
starring stirring
stars stirs
suave swerve
tarn tern
tarns terns
vast versed
yarn yearn
yarned yearned
yarning yearning
yarns yearns