The /ŋ/ sound is spelled with <ng>. The /ʤ/ sound is spelled with <dge> or <ge>.
This is a contrast between a velar nasal continuant and an alveolar affricate, both voiced and only occurring in final or medial position. It is not a problem. The majority of the pairs are verb -ing forms contrasted with noun derivations in -age from the same root like assembling/assemblage.
The mean density value is 1.2%. The lists make 68 semantic distinctions, a loading of 88%.
adding adage appending appendage assembling assemblage bagging baggage banding bandage bang badge banger badger bangers badgers blocking blockage bonding bondage braking breakage breaking breakage bring bridge bringing bridging bung budge bunged budged bunging budging calking corkage corking corkage carting cartage cleaving cleavage coining coinage cording cordage covering coverage cribbing cribbage damming damage dosing dosage doting dotage draining drainage drifting driftage footing footage fronting frontage garbing garbage harbouring harbourage hauling haulage ill-using ill-usage leaking leakage levering leverage lightering lighterage linking linkage long lodge longed lodged longing lodging longings lodgings lugging luggage manning manage messing message packing package pasturing pasturage peering peerage pilfering pilferage pluming plumage porting portage posting postage potting pottage pounding poundage pressing presage ring ridge ringed ridged ringing ridging roughing roughage salving salvage seeping seepage shorting shortage slung sludge spilling spillage spinning spinach steering steerage stopping stoppage storing storage suing sewage swanning Swanage tilling tillage tonning tonnage using usage vesting vestige wanting Wantage wasting wastage wrecking wreckage
John Higgins, Shaftesbury, December 2010.