I think Roger, as usual, presents good advice.
The question of "how many sails do I need, and how much money do I have to spend" is always tricky. It is not just "what is the ideal sail now" but also "how am I going to grow my quiver of sails".
As a one sail solution a 7.5 may work reasonably well. But then when you grow your quiver to two sails it will not be good neither as the biggest, nor the smallest sail.
A two sail solution should have a biggest sail of 8.0-8.5, and a 6.5 as the smallest sail.
Then again, when you go to three sails the setup should probably be 8.5, 7.0 and 6.0. This is ideal, but costly. to make it worse it typically requires three masts (490, 460, 430).
I know from own experience what a pain (and expense) it is when you have to change the spacing between your sails.
It makes sense to check out the required mast lengths. If your biggest sail is an 8.0 (or slightly bigger) you may manage with a 460 as your longest mast (with a long extension a luff of about 500 cm is realistic).