I have access to both Apple and IBM ppc64 machines and could check if you provide paste'able Forth code. :)
Apple's OF for 64-bit machines (version 5.x.x, on G5 machines) is a 32-bit OF.
This may not be applicable to sparc at all but again someone with access to the hardware would have to confirm.
In its present form, the patch seems in no way limited to ppc - you might want to look at the [IFDEF word or so if that's your intent.
I would recommend all these words for BootX support go in a bootx.fs file, which is only used where needed. You do not want to always include all these weird apple-isms :-)
Segher