Awesome! I’ve done a handful of trips like this, agree with what folks are saying about the gradients, my advice would be try and have 2 big days 2 weeks in advance as a ‘specificity’ training of the 2 big days in Spain if you can (perhaps a big ask, but best case scenario).
If you don’t have sustained climbs it would be best to do it on a flat route with friends and design a route that has 4 20 minute sections or so to more or less get you to the 2500 m. I’d go relatively hard the first day, then for the second come back and do the 2700m facsimile at high zone 2 or tempo and then try and do the last section as hard as you can. This second day of being able to put out at least sustained tempo effort on tired legs is the critical part in getting specificity training + confidence for the trip itself.
After that try and rest heading into the big trip doing some short high intensity efforts.
In my experience this sort of ‘do the sort or riding you’ll do on the day’ training not only works really well physically but gives me tons of confidence and allows me to enjoy the trip more by knowing I have enough in the tank to put in some quality efforts on the key climbs.