you get a stronger spark with the DIS system, and it's more reliable than the TFI setup used before that...
you probably can, but it pretty much does its own thing and just works, adjusting the timing is overrated, the curve in the ECM for the DIS ignition is plenty sufficient.
now if you are talking about setting up the engine for something else and going carbed or something, I believe the distributor would hit the intake manifold if I remember right, and an older carbed manifold won't match up to the 8 plug head.
I'm running DIS on 4 plugs on my '86 thunderbird turbo coupe engine, I purposly went this route to avoid the TFI that was on the '86 engine