If you are chasing tin-worm on your car, and the 100k mile is solid, it's a no-brainer just to buy it as the DD.
To restore your current CRX is only a viable option if you do the labor yourself and that probably means weeks and weeks of work, if not months and months. That would give you time to source the specific engine you want.
I can understand wanting to keep and restore it, as it has sentimental value, but in the meantime you have to get to work, if only to pay for the restoration and/or engine swap.