Some helpful historical stats regarding #1 seeds
Over the 24 seasons there have been a total of 192 Sweet Sixteen games -- 8 per season for 24 seasons.
The four most frequent seeding matchups have been --
1 vs 4 -- 34 matchups -- there are 2 such matchups this season (Pitt vs Xavier and North Carolina vs Gonzaga)
1 vs 5 -- 32 matchups -- there is 1 such matchup this season (UConn vs Purdue)
2 vs 3 -- 29 matchups -- there are 4 such matchups this season (Duke vs Villanova, Memphis vs Missouri, Michigan State vs Kansas and Oklahoma vs Syracuse)
2 vs 6 -- 23 matchups -- there are no such matchups this season
Thus the 4 most frequent matchups account for 118 of the 192 Sweet Sixteen games, or 61+ percent of all Sweet Sixteen games.
The other matchup this season matches a 1 seed (Louisville) vs a 12 seed (Arizona), a matchup that has occurred 15 times in the 24 seasons.
1 vs 4
The # 1 seed has won 24 of the 34 matchups straight up (70.6 %) but is just 19-14-1 (57.6%) ATS.
1 vs 5
The # 1 seed has won 27 of the 32 matchups straight up (84.4%) but is just 13-16-3 (44.8%) ATS.
1 vs 12
The # 1 seed has won ALL 15 of the prior matchups straight up (100%) and is a solid 9-6 (60.0%) ATS.
2 vs 3
The # 2 seed has won 19 of the 29 matchups (65.5%) and is 16-13 (55.2%) ATS.
Maybe you should look at some of the other seed matchups.
Hope this can be of some help with your plays.
GL.