I've got a few thoughts on your trip.

Riding from Texas to Vancouver would be a lot of fun. I don't know your exact route, but it won't be monotonous. Enjoy it.

Your 40-day timeframe with 60 to 80 miles a day might be a little ambitious. Those distances are possible, but when you get into the mountains, the climbs will shorten your distances. If you're doing 60 miles in a day when crossing a mountain pass, you'll notice it.

I'd strongly suggest you give yourself some rest days and some additional days. This will give you a lot of peace of mind if you have any complications along the way. A minor injury, a problem with the bike, a strong headwind, rough weather or fatigue can slow you down. If you need to do 60 to 80 miles a day to meet your schedule, it will be difficult if you fall behind, even for just one day.

As for the bicycle, how will you carry your gear? If you're carrying your own gear, you need a bike that's up to the task. Ask at your local bicycle shop for some recommendations. There are some fine touring bikes on the market. They're built to handle the loads you'll be carrying.