It might seem a good idea to go oversize to achieve a better fit, but it's not in my experience.
I think OEM sizes were 3.96 mm to fit a 4 mm nominal sized terminal, so I'd personally seek them out or go with the commonly available 'Japanese size' 3.9 mm bullets as Toddy recommends.
I'd be interested if a real 'proper' assembly/crimping tool is available rather than always tending to solder, crimp & heat-shrink over....as I do
I think my prejudice to modern crimped auto electrical fittings has a lot to do with the habit, despite owning good tooling for the purpose. Crimped fittings might be sound electrically, but they look gash to my eyes....