I am in the midst of this exact project right now!
In theory, this is true. In practice, I have found that it would have been far easier, safer, and cheaper to just have purchased a commercial battery pack from Newegg. The 18650 cells can be very dangerous and frustrating to work with. If they are not handled properly, they will explode and catch on fire. (Don't ask about the melted battery pack on my workbench.) I built a spot welder to attach them together, but this cost almost $100 by itself. Theoretically, you could solder the batteries together, but with how reactive they are, I would not even consider doing this. I think the 18650 cells cost me $30, and a charger for the cells cost $10. If I had just bought a $60 battery pack, I would have been much better off.
Of course, I am having tons of fun figuring out how to do the project, and I am enjoying working on it. From a monetary standpoint though, I'm not sure it is worth it, unfortunately.
I hope to make a post about my battery as soon as I assemble a battery pack that doesn't try to catch on fire! I think it will be really exciting to use my Clamshell without being tethered to the power adapter.
The actual pin assignments do not seem to match up. Below is a diagram of the actual RAM chip socket pinout from the 128k/512k schematics that are available. As you can see, they do not match up. I looked a while for a solution, but I got too busy a month or so ago and never found one. Maybe we can find a solution now.
One more piece of information that may help: the system failed "overnight." Literally.
The evening prior I had been working on the machine, got the system loaded on a SCSI2SD, etc. Shut down. The next morning -- nothing.
What would cause this kind of abrupt failure?