Powered correctly, they will absolutely be an upgrade to your current setup, especially for projecting out to your rider in tow. They also sound great close in when surfing or at the party-cove.
Mounting hole diameter - 5.688"
Grill OD - 6.80"
Woofer mounting depth - 3-7/8"
Horn mounting depth - 7-3/16
If you cans are blunts, then you should be good with anything over 3-3/8. If your cans are a bullet shape, then you will need the can to be longer then that. As you see in the pic above, the cross-over on the end of the horn is about 3.5" square. Depending on the degree of taper, you may need 8+ total depth.
What model amp do you have?