Possible source for fast DRAM ICs

[Quagliarulo]

When overclocking a '060 we are often forced to have the RAM work at half the processor's clock rate. This made me think of a way to create custom SIMMs with faster RAM chips.
DIMM sticks are made up of SDRAM ICs that we can't take into account, because they are synchronous (data is valid at a certain predictable time). But I found out (although I'm not perfectly sure yet) that there was a line of PCs (called "PC300 GL") made by IBM that used custom 168-pin DIMMs with very fast DRAM ICs on them.
If this was true, we could come up with a custom PCB layout and make SIMMs suitable for 80 - 100 MHz operation.
Just wanted to share my idea, as I haven't got any overclockable '060 nor the equipment needed for such a job.