As this picture shows, the Pilots uniform was almost complete before the end of the 1968 post season. I say "almost" as there are a few differences between the prototype that Joe is wearing and the road uniform that they wore in 1969.
The first difference is the cap. Although its partially cut off in the shot above, the "S" on the cap looks more like a reversed "Z" than a "S". Here is a different shot of Joe in the cap:
The second difference is the lettering. First, the prototype has "seattle" straight across the uniform, whereas the 1969 jersey had the name arching across the front.
The second difference is the "s". Just as the cap features a "s" that almost looks like a reversed "z", so too does the jersey. And finally, the "t"s appear to be smaller on the prototype than what they actually wore in 1969. The letters also appear to be tilting to the right on the prototype whereas they appear to be more straight on the 1969 jersey.
I like the shot of Joe with both of his uniforms, and appreciate the fact that since this picture shows him in the Pilots uniform during the World Series, it gives us an idea of when the Pilots had almost finished designing their uniform.