I'm kind of in a similar situation. Have a 120 mile, 11k feet of climbing ride on June 15. Longest ride to date is 65 miles. I'm going to push some longer easy rides, including a century this Sunday, but it's going to come down to pacing for the June 15 ride because my saddle time is going to be pretty long.

If I were looking at that ride coming up, I'd two two longer days in a row to at least start some adaptation in that direction rather than a long/short.