There are always reasons it might not fit ‘right’ depending on the way the person mated the aluminum tub to the firewall BUT the hardtop ‘should’ fit. I put a hardtop on a previous truck that was an Aquala tub, was a ‘74 too.
Might need to cut some off of the b pillar tubes that go down into the tub and you will need to trim the hardtop lip in the rear corners as the Aquala tub has a triangle piece there. Very small thing and easy to see when you go to place the sides on the tub.
see my "Time Machine Build", in the signature line. do your measurements at the doors before you split the body from the cowl, and make sure that you get the same numbers when you mate the Aqualu body to the cowl. no reason it should not fit.