Anyone that knows me will tell you it would be gloss!
OK, you want patina. Peint it in 2k top coat, not base coat & clear. If you want it to look old then a join in the paint will look more authentic between the colours. The Beugler pinstriper will make it look more original too.
Paint your main colours on & flat the paint back with 1200 wet paper. It doesn't matter if you go a bit far in places it will add to the effect.
Mop it back up with G3 to a semi shine finish. Paint on the other detail, use as much brush sign writing as possible & run the mop over it after a day or so very lightly, it should take some of the sign writing off making it look aged.
If you use any decals, adjust them in photo shop & fade or even distress them before printing. It is hard to age a printed graphic after as most have a 10 year garuntee.
It can be done...