According to a couple short mentions in the 1992 Sbike Speedbook, "Daytona" is the name Sbike gave the bikes with the high-end alu frames. Those were the frames that were hand-made by Verlicchi and then built in Lugano.
The 700c is the first of the Daytona models. On some of them the Daytona name is even on the chainstays.
Later models were the 71x-72x range and the full-suspension models.
I'm not sure about the 80x frames. Those are alu too, but they have the same chainstay model as the steel bikes.
I never came across an 80x IRL, but from the pictures I have seen of the welds I can tell with almost 100% certainty that those are made by Verlicchi too. That would put them in the high-end range, but the styling looks so much like the low-end bikes that I wonder if they really would have given it the Daytona name.
As for the 704-724 thing, is that an Altus A-10 set in that top picture? The mech sure looks like one and the rest looks exactly like the set on my 503 as well.
If it's A-10 indeed, the last digit is wrong. It should have a "3" at the end.
However the 0 in the middle could have been correct, I have
a pricelist for Belgium and the Netherlands which suggests that the 706 has LX and the 709 has XTR parts.
The more you look into the model numbers, the less sense they make.
Is there any way you can still contact that former owner? I have a one-off Sbike frame, possibly a prototype, that I'm trying to get info on. Looks like an in-house Lugano job, because the welding looks nothing like what Verlicchi does.