The Alnico II bridge pickup has a lower more vintage output than the 498T and will be much smoother, lacking the upper midrange spike that the 498T has. The Alnico II neck model is in the same ballpark (output-wise) as the 490R, but will probably sound crisper and clearer. The problem I had with the 490R/498T combo was that the bridge sounded harsh and piercing while the neck sounded woolly and muddy - worst of both worlds! The Alnico II Pro set will give you a much better balanced and clearer tone.
A really worthwhile change, while you're doing the pickups, would be to change all the pots to CTS 500K audio taper. They will further open up the tone of the guitar and give you more precise control over your volume. A '93 LP probably has 300K linear volume pots - changing to 500K audios will make a big difference and really show off those new pickups!
And if you DO change the pots, it would be rude not to do the tone caps while you're in there - .022 Orange Drops are nice.