I think 64 miles per day is completely reasonable, depending on how far you can confortably ride in a day. When touring, my usual day is 80-100 miles. After factoring in rest days, my average drops to around your 64 miles. If 64 miles is a full days ride for you, then 45 days without a break may be too ambitious.
On the bike, I figure on riding 12 mph plus 1 hour for every 1000 feet of net elevation gain. This formula for me includes all my time off the bike, too, such as sightseeing, rest breaks, and lunch. Therfore, my 80-100 mile days are leisurely 6-10 hour rides depending on terrain and daylight. I can, and have, gone much faster, but then it's just a long bike ride, not a tour.
I don't think you need to be in great shape, but you should be in reasonable shape. Is there a local club (not a racing team) that you like? Consider riding with them and askig about touring. It'll be a great asset to you if you can find an experienced tourist nearby who can help you with the planning and learning.
A touring bike is best, but any bike can be made to work if you want it to. What bike do you have now, and what are you planning on taking with you? If possible, show it to your local touring guru. Do you want to ignore the bike during the tour, or can you complete the tour in spite of the bike?