Found a pretty severe bug that came up in testing this tool. The last byte of each 6 byte entry was wrong (it was always zero). The is the byte that indicates what resource file (RESOURCE.001, RESOURCE.002, etc) the game resource is in - so valid values are 04, 0C, 10, 14, 18, etc - corresponding to 001, 002, 003, etc. These values of the resource file #s are packed into the left 6 bits of the byte.
I've re-compiled & packaged it up.
Another note: It is interesting how Sierra MAP files are put together. Sierra put commonly used resources in many of the resource files, to prevent disk swapping. When looking at their MAP files, they put all the same resource references together. So if a resource was packed into 4 difference resource files, the MAP entries would all be placed together.
This tool creates the MAP by going through each resource file linearly, so all the resource.001 MAP entries come before all the resource.002 entries, and so on. Essentially, the MAP is built in the order of how the resources appear in the resource files, in directory listing order.