Alejandro,
In the very first line of the BIOS , you can change bus speeds.
Do it in only 1 MHz increments and play with it by slowly increasing it to see what you can do.
For instance 101.
The problem is that the EVA 200MHz bus will only take a small amount of increase.
Usually people are able to get 10MHz increase or less, before instabilties occur.
Put your cpu multiplier back down to normal and play with the bus speeds a little.
I have found that my cpu, a 1.1 will only go to about 1300MHz before the L2 cache starts getting problematic. So what I do is change the multiplier to 12.5 then run the bus at 105MHz.
So this is what my system is doing
12.5x105MHz= 1313MHz.
The memory is set to PC133. It also gets an increase from the 105MHz bus so my memory is running at 133MHz+5MHz=138MHz.
The EVA bus increase gets doubled so it's running at 200MHz+2(5MHz)=210MHz
There's a lot to take into consideration when overclocking a TBird system.
But the benefits are well worth it!