I'll be traveling to Montana Headquarters first because I always wanted to see the kind people there.
Do you mean you will be starting there? If not where will you be starting your tour?
I have looked at different maps from ACA but I can't seem to find the rights once and there is always the option of using Google Maps and I could buy myself a bike gps unit.
There are a number of options to get from Missoula to the coast. Pick the one that best suits you plans I'd recommend the Pacific Coast route south from there.
I recommend really looking at the specs before buying a bike gps. The batteries are usually internal and don't last all that long. I have had better luck using a handheld model that you can change batteries in.
Using a smartphone is another option. You can carry spare phone batteries and/or a "power wallet". I recommend turning the phone part of the smartphone off except when actually making a call. If you use map software for your phone that lets you pre download the maps you need you can run in airplane mode saving battery life. Phone batteries die really fast when there is no signal and they are searching for one.