To answer your question about the NiCd batteries. The short answer is; yes!
At my former employer I used to get NiCd battery packs that were taken out of service as well.
Do a search for a long time forum member " Norm" he is the guru of putting that packs to some great uses.
Now, the 60Ah ones are much more useful.
There is some things you will need to find out and let us know too.
Are those batteries solid types or wet? There are some considerations both.
Another great member and former Moderator "TomW" has posts about his large NiCd packs too, so you might want to read up on his as well.
When you say there is enough to make 12Vdc, how many is that specifically?
NiCds both wet and dry are when fully charged and resting at 1.36 - 1.42 per cell and quickly drop to the 1.25 per cell when under a load.
You can quickly see that these voltages are under the normal voltages for LA based batteries, so you will need to make adjustments for the differences. Most of the larger inverters will complain about this.
The packs I use are solid and only 16Ah max, but they are great for heavy or high drain situations as they hold their voltage until nearly dead.
NiCds can also take a nearly complete drain and bounce back like a happy puppy :-).
IF you have 11 or 12 of the NiCd batteries, you could actually mimic a L.A. system by using them to account for the lower voltage or what I know of as voltage sag.
Just know that NiCd are constant current charging batteries so you will need to adjust your thoughts on a charging circuit.
A picture of on of the batteries would be great.
Still,,, with the little amount of mental change, those are a could be a great addition
Cheers
Bruce S