I think black letters is how I would do it. Here is a quick mockup I did to get an idea:

 

It may seem strange, and I can't get pics because the old man trashed it long ago, but the tail gate on his 84 that is desert sand and beige had ORANGE letter from the factory... The red would pop, the black is subtle. It depends what look you want.

 

I wonder if that orange was featured elsewhere on the truck, like in a pinstripe or something.

My 1981 F-150, dark caramel metalic, has light orange letters due to the fact that my main explorer stripe is also light Orange.

Trucks without the Explorer package got white letters...

There are always exceptions...

 

I've never seen black ones in my life. They must have only ran them for a couple of years.

 

Nope, no orange anywhere, except the lettering. still have the truck... he had damaged the tailgate beyond any possibility of repair. The stripes it does have are the body colors, just alternated to show up. It is an XLT package.

 

Orange is unusual, without any other orange, but so is purple.

I've seen purple factory letters as well.

 

My black 81 has orange letters. It also had orange/red stripes going down the side and surrounding the word FORD on the tailgate at the edge of the small panel the letters were stamped in.

 

That would make sense why it had orange letters. It matched the orange stripe.

Just orange on it's own is rare.

 

I've seen orange letters on a black truck before. Of course, that truck was an Explorer package and had orange stripes as well.
I've also seen black trucks with the red/orange striping on the sides and tailgate.



As for the red centers in the wheel caps, I still think they will look good. My son-in-law has an 86 Bronco II with the factory wheels similar to what grayf100 posted, and it has the red centers for the rear wheels, and the centers of the front lockouts are red. That BII is white, with blue stripes and interior. Only red anywhere else on the truck, is tail/brake/turn lights and dash warning lights.
The black centered factory caps were used on 93-95/96 rangers, but on a different style wheel. I was thinking they were, and just saw one that had them on it.
I'd like to get a set of those red centered caps for the wheels on my B2300. Someone put 15 x 7 factory Ranger alloys on it ("deerhoof" style) but retained the larger dark gray center caps that cover the lugs from the stock steelies. This truck is the tan-ish silver color, and the only "shiny" parts are the wheels. Has the full grill/bumpers/door locks and handles blackout treatment like the XLS trucks from the 80's.
Of course, changing to the caps that use exposed lugs would also mean changing the lugs. The ones it uses now are just annodized, since the center caps snap onto the lugs.

 

Yes, and that is why I originally suggested to Greyf100 the red tailgate lettering with a red stripe. The red lettering would be my preference, but only if it also had a red stripe somewhere to accent the tailgate lettering. Otherwise, the red center caps without any other red anywhere on the truck wouldn't look like something Ford would do.

Greyf100 doesn't have the "Lariat" package, so he wouldn't have the red LARIAT emblems to tie into the red center caps. However, his truck did originally have a double red stripe on the side of the door to separate the two-tone. If he were to keep this stripe, I think the red center caps would look great along with the red tailgate lettering.

 

ordered black letters....

The red stripe wasnt factory original, it was painted sometime after the Original Owner bought the truck.

 

But it is exactly what Ford did. During the late 70's, 80's and into the very early 90's all trucks that had the optional factory "styled steel" or alloy wheels got the red centered caps, regardless of the trucks color.
I'm not sure why they chose the red centers, but I suspect it was simply because the manual lockouts on 4wd trucks were red, so it seems logical to make the caps red centered to match.

I'm not saying your thoughts about it looking odd aren't valid, just that it would actually be more factory looking than using anything else.

Just something to add here. I had an 80 Ford Courier that I had painted red/white/red two tone (never available factory with 2 tone paint). When I had it proffessionally "trimmed" the guy suggested using a 1/2" silver stripe at the paint break lines, with a narrow blue in the middle. I thought it sounded silly, and that a red one would look better. He did one fender with blue, and one with red, then had me decide which I thought looked better. Derned if the blue didn't look better, and the red looked awkward. There was not anything else anywhere on that truck that was blue. The blue didn't "stand out", it actually just blended right in, and looked like it belonged there. I was very surprised by what I saw when I compared the 2 fenders. He wasn't though.
Sometimes, having an "out of place" color for accent, just works so well, it goes unnoticed.