Others will know, but I don't know whether you should be on a 96 or 98.
But regardless of hubs used . . . much of it depends on the sprockets and on whether you are looking at worn, or unworn, primary and rear chains.
First thing I'd do is see how worn the primary chain is and thus how much adjustment there is left on the gearbox, and at the rear wheel.
If using a 96 with the primary nearly worn out and the gearbox therefore right back, then a shorter than 98 (if that's the 'correct' length) rear will have compensated, especially if that is also knackered. Once upon a time, people (not the sort of people on here of course!) would remove a couple of links to get a bit more mileage out of a tired rear . . .
A 98 might be needed with a new primary chain 'shortening' things up front though, as it would also with maybe a larger gearbox sprocket if you are by any chance equipped with something a tooth or more smaller.
On some bikes I have had to swap lengths according to the gearbox sprocket changes - or indeed change the length of the primary if swapping crankshaft sprockets. With, again, potential consequent effects on the rear chain length.
Sprocket options are many, so there probably isn't a definitive answer to the Q - but what you DO want are lengths that are a comfortable fit for both chains, unworn, with the gearbox in a sensible & fairly well-forward position and with the rear wheel near the front of its adjustment. If I got there, I'd be happy regardless of what any book or bar-room expert might have to say on the matter.
Worst case, a cranked link (usually on the primary) - but not unless you have to. Some sprocket combinations make it unavoidable, and some machines of other marques even specified odd-numbers of links for primaries.
