Regarding JiffyDOS-Overlays-Modified.pdf, Mint from CommodoreServer helped me so much with that since I'm horrible at using "the Gimp." Basically I wanted to redesign the C128 keyboard overlay so that:
Ideally, the dot density should be fixed on the lower row--that's for another day. (We'd probably have to find a different font and re-type the text.)
I'd say we succeeded in making a nice replacement template! Something similar may be done for the C64 keyboard overlay, but there is limited space on the left side of the template.
January 30, 2015: Added the demo/utility disk v2.4 for the Hearsay 1000 speech synthesizer as per request of this Lemon 64 thread.