Still blinded by the chromite.
The Ring needs a road as a start and all else would fall in place.

To run you need to learn to walk and to walk you need to crawl.

Crawl: With the road Noront would have a working nickel mine which both would provide initial jobs and no boom needed.

With that would come an impetus towards chromite mine construction.

Walk: Taxes from Noront mine and road jobs would start an inflow of cash for the government to contribute toward a railway. OK not much initially but you use that as an assured income towards financing.

Run: With chromite mine or mines built some serious money would flow into both government coffers and return some of the money initially invested for infrastructures.

No need for a commodity boom, just start the opportunity to build. And no Marshall plan needed just some common sense applied.