You could use that in an active setup with some 4" comps.
I think the standard sizes are 6.5, 4 and .75 inch for the bass/mid/tweeter units. As mentioned above the woofer space is massive.
In installed those size replacements with no major issues. The only area of concern is the mids, the depth isn't very much so some beefier units are too deep for the door card to fit back properly. Mine are 41mm and fit but again a search will clarify the max.