WHDLoad is fully compatible with all 020 to 060 CPU's. Some games will work with a 68000 but some need a 020+
WHDLoad is a degrader tool to make old games work on hardware and software which would normally not support these games.
Example: Seven Cities of Gold from EA. Released in 1985 for the Amiga 1000, it only runs on a 68000 CPU, with 256K Chip, Kickstart 1.1 and below. With WHDLoad I can run it on my A4000 with 68060/66MHz CPU and 272MB Fast RAM on AmigaOS 3.9!
Note: Some games will run better on a 030 vs a 060 but that is due to the slave author not doing the slave correctly. One game I remember that had this issue, and has been resolved with an update was Liquid Kids. It only ran correctly on a 030 and would have gfx glitches on a 040+. Now it works perfectly.