The DT three-pawl system was a perfectly serviceable entry level hub, nothing inherently wrong with it and unlike most hubs at that end of the market you could easily get spares for them.
The slower engagement meant a chunkier mechanism with bigger teeth which tends to offer better long term reliability when neglected compared to faster engaging systems with shallower teeth, all other things being equal. Swings and roundabouts in other words.
Thanks @hatter – do you know the part number of the kit or the description so I can track it down ?
The kit to convert an old G1800 to Ratchet LN would be HBDTLNKIT07 in XDR and HBDTLNKIT08 in Shimano HG 110-speed road.
You will need both a pawl and the ratchet ring nut tools though so, as mentioned above it may be a shop job.