You definitely have the riding strength, N2. Just extend a few miles each week and work on your nutritional balance and you'll get there. If you did 76 miles in 5 hours (with breaks), that's pretty fast for a first time. When I do a century, I tend to take them slowly - lets my body take its time burning its own fuel rather than needing to carb up so much. My first century took me something like 10 hours.
But like m.e. said - you don't have to feel like you "need" to do a century - just do what you enjoy. If you want to get to a century, awesome
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