While re-build costs are fairly comparable to costs of a crate engine, many engine builders require a core, and the core costs can be fairly high. If you do not have the same core this will add to the cost and might not make it as desirable as it can be.
While I would probably be more of a 385 series fan, I am not too sure I would discount the idea of re-building the FE. This would dbe the easiest thing to do and probably the best bang for the buck.