If you use 80% full gloss and 20% semi gloss mix P'Thane then it will match the original lacquer finish perfectly.. just the right amount of shine.

With the text and of course some very good colour matching, you can use a clear contact over the area.. use a ruler to cut along top and bottom edges of the text ( so text is masked off with clear).. spray, then remove the contact, it will leave the text in full... any planking between letters can be painted out with a fine brush. If the text is small then the planking will hardly be noticeable.

Ratio to make up a wash? Couldnt tell you... its done by eye, but its thin enough to leave no brush marks when dry and also if say washing a blue and you inadvertently make a small wipe over some white then it hardly notices... so.. er... pretty thin?