This motherboard likely came out before the DX2 was released. Any of the 5V 486s should work fine in your board, so a DX2 overdrive isn't even necessary. Just use a regular DX2. AMD (and possibly Cyrix) did make 80MHz DX2s that run at 5V as well, but I can't really recommend those as they get hot.
Your best upgrade path is probably an AMD DX5-133 on an upgrade adapter. Those were produced in mass quantity, and if you look you can find them for about $30.
"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium