The QuickPak 060 is a fantastic accelerator, and is the ONLY Amiga accelerator that actually takes advantage of EDO memory. It's designed to run up to 66MHz but I own a 68060RC50A rev 5 CPU that is known to overclock very well so I replaced the oscillator with a 36MHz part to obtain a 72MHz bus clock speed. 100% stable and cool to the touch. Not one chip on the whole accelerator gets hotter then warm.
If I had 50ns RAM, I could probably do 80MHz.
Still, at 72MHz it has been running for months without a single reboot or crash.
On the other hand, I also have an A3000T/060 that I use with a Video Toaster 4000. It has a CyberStorm MKII 060 @50MHz w/CyberSCSI. Even with the CyberSCSI removed I can not get a stable overclock to even 66MHz. I've tried the CPU from my Quickpak with the same results so something on the MKII is limiting the overclock. The AMD MACH GAL's get almost too hot to touch at 66MHz and the accelerator causes lockups frequently when overclocked. Perhaps with some small heatsinks and a good fan I could keep it stable, but who cares? I do all my lightwave rendering on the A4000T and use the A3000T for video switching, so the 3000T does not need to be any faster then it already is.
Anyway, the Quickpak 060 ROCKS and I highly recommend it to anyone. They _will_ work (and fit) in an A3000T, I have tried it myself.