So that means you’ve got 30 years invested in maintenance of your old projects and libraries.
I had a quick look at both “amscad” and “pcpro pcb”, but neither get many hits in a search engine and it’s seems to be software that has never been used by a lot of people. This also makes it unlikely that some other KiCad user has written scripts to do some kind of conversion. (There are some 80+ “side projects” around KiCad, from small utilities to conversion or backup scripts, alternative schematic entry, etc…
If your old software gen generate Gerber output, then you can back-import the PCB of a project into KiCad. It’s not perfect but you get about 80% of the PCB for 10% of the work needed for the conversion. I wrote a faq article about doing this: Reverse engineering KiCad project from Gerber files
It’s unlikely there are better importers, but KiCad does have quite reasonable libraries, the built in editors for both the schematic symbols and footprints are quite good and they have the same “working style and feel” as the rest of KiCad and this helps a lot with getting used to them. Schematic symbols are simple, it’s usually just one (or more) rectangles with some pin information (and there are external programs to help with organizing that pin information). KiCad’s footprint editor has a nice array function and a way to copy footprint information (such as size SMT/THT, etc.) between pads and is quite adequate for simple to moderately complex footprints.
If you have very complicated footprints, then the combination of FreeCAD with the “StepUp” workbench could be a viable option, but there is quite a learning curve ahead to work with FreeCAD.