Overclocking the Derringer Accelerator.. which 68030 is best?

[Lockon_15]

MC68030RC50C is still being produced by Freescale. AFAIK, it's ROHS and LEAD free and generally runs at lower operating temperature.
 
Overclocking is possible, but probably not advised. I guess it won't make much difference even if you managed to get faster RAM. Main stability issue is glue logic (CPLD) chips which cannot provide safe response if overclocked above certain level.

[Lockon_15]

Code-compatible should be regarded only from instruction point of view, since 030 is optimized version of 020.
Like Piru said, it's not a drop-in upgrade option.
 
I know it's hard, but you have to stay away from Windows-Intel philosophy