The cool thing about Mac Garden is that you can select a year and get a list of all the games made that year. Look for games around 1989,also, look for games with a black and white picture. Here's another website that has a small collection of neat games including one that is not carried by Mac Garden: http://www.applemachome.com/Downloads.html

To answer your second question, you should be able to dual boot 6.0.8 and 7.5: http://www.jagshouse.com/dualboot.html