I know it was several pages ago, but I'm one of the guys mentioned who's converting a 1974 Gottlieb Big Shot to SS control using a P-ROC. (Don't worry though, we're trying to make unnoticeable to the casual player, including the mechanical score reels, chimes, classic stepping bonus count down, etc.) We'll have this thing in the P-ROC booth and are doing a talk at the Chicago Expo this year if you want to see it.
You can follow the progress on our blog, here's the link to just the Big Shot-related posts.
We're also the guys behind the open source Mission Pinball Framework (also discussed on Pinside) which we hope to make easy enough for even non-programmers to use to build games. There are a lot of EMs out there which are super cheap with dead guts, so we're hoping this can resurrect some of them. Most EM games are simple enough that they can be "programmed" completely with our text-based config files. Yeah, you'll need a P-ROC or a FAST controller, but the host computer requirement can be handled with a $39 Raspberry Pi that you update via Dropbox. Plus you can do all sorts of modern things if you want, like ball save, light shows, and beatbox style music using the chimes, knocker, and pop bumpers.
BTW I love EM games which is why our modernization is not involving sound modules or digital score displays. (Those things always seemed so out of place to me.) My first pin was a 1968 Williams Lady Luck (which I still have). For Big Shot we gently removed the EM guts intact which we hope will be useful to someone needing the parts to bring another machine back from the dead. (Well, except for the reels and chimes which we're still using.
And yeah, to the person who said we wouldn't be able to wire this in a weekend, they were right. Took about 100 hours. And no, we didn't destroy the playfield by sanding. 1500 grit using alcohol to wet sand plus carnauba wax and that thing is looking almost brand new!
Now, onto more important things... This was my first computer in the 80s. I didn't have the cassette interface module so I would write down all my programs on note paper and leave the computer powered on all the time, and if I accidentally lost power I would re-type them all from scratch. I still have that thing actually.. wonder if I can write a USB interface to hook it into the P-ROC?