I did a build of the latest bleadperl, and aside from some symbols that should have been skipped in makedef.pl, it worked fine, all the way through to the perl MPW tool for all four compilers. I didn't go further than that.
Find::File is severely broken in 5.6. It was rewritten from scratch, and apparently without any thought given to portability. This is troublesome. I guess some of the responsibility is mine; when it was first submitted to p5p in late 1999, I saw the post, but never looked at the code. I don't know what should be done about it. Our choices that I see now: 1. fix the existing code (ack), 2. roll back to the previous version for 5.6/5.7 (not likely, since there were new features introduced), 3. roll back just for MacPerl (unattractive; see 2.), 4. rewrite from scratch again (ack!).
InstallBLIB had a little issue, that I fixed a long time ago, but didn't roll the change into the right copy or something. Thanks, Thomas.
File::Copy needs porting. It is actually not so bad, but to do syscopy it needs Mac::MoreFiles. Ack. Mac::MoreFiles won't be available when File::Copy is used in PerlInstall before Mac::MoreFiles even gets built