Cracked case and Airmelt crank...

[TomeHill79]

Despite having a low time rear engine with great compression #'s (75/80 is lowest of 6) and no metal in the filter but my AP/IA during annual inspection found a small crack in one of the case halves...
My rear engine is a IO-360-C with a Airmelt crank

I'm looking for advice on buying a new case, crank and having my engine repaired or taking the plunge on a Factory IO-360-CB6B for $40k and a 1700hr TBO. Are there any other options that you would suggest?

Thanks in advance