+1 to red. I think it will look great. Although yours is more pewter, I think it will turn out similar to the black Motobecanes with red lug lining--an attractive look IMHO.

I recently did some lug lining on my Nishiki. I used a Duro artist brush (#1 size). I opted for hand painting for two reasons: 1) to better match the paint color, 2) I don't mind the slightly imperfect look of hand-painting.

The red on your bike's decals seem to be slightly orange. Maybe it's just my computer screen. It may look off if you paint with ferrari red paint pen.

Though I don't mind the hand-painted look, I do have a pretty steady hand and used a beat up gas-pipe frame on which to practice first. I also had a rag with a touch of paint thinner handy just in case (though be careful not to use it on the original paint more than necessary). This was my first attempt at lug lining, and I'm happy with how mine turned out. Slow & steady!