Well, Ziff-Davis CPU / FPU enchmarks are quick and their results are quite reliable. They don't use MMX, SSE, 3DNow! etc.
When I test overclocked CPUs, I use a simple yet very extensive "benchmark". Boot an old Linux / FreeBSD / NetBSD release and compile a generic kernel with 'time make'. Compilers stress ALUs, branch prediction, caches, memory. It takes 3120 seconds, give or take a few, or 52 minutes to build a generic NetBSD 2.1 kernel on a 300MHz Cyrix 6x86MII + FIC VA-503+ (VIA MVP3, 1Mb cache) + PC100 SDRAM 2-2-2. If a CPU doesn't segfault or produce some other error in the process, consider it a successful overclock. Many overclocked Cyrix CPUs can do benchmarks in Windows yet fail in less than 2 minutes of compile time.
180nm PR400 and PR433 Cyrix 6x86MII with gold tops are quite rare, but there are more common mobile 180nm PR333 with gray tops. These are earlier steppings than gold tops. Although they cannot do 300MHz usually no matter what voltage.