Reseated LCD cable on the inverter AND LCD itself. Nothing.
Edit: Is a 160 inverter compatible with a 140? Maybe I should swap them out and see what happens. I really dont think its the ribbon cable since I tested for continuity. LCD doesnt appear to be the culprit either just from looking at it. After looking at Apples service manual. Apple seems to think the LCD or interconnect board. No mention of the inverter. Also mentions a display cable shim.
In addition to that it would also depend on the two respective drives having exactly the same (or at least close enough) low-level formats and compatible embedded servo information. I know places like Drivesavers sometimes do board swaps for low-level recoveries, but so far as I know they do them between exactly the same models...
I mean, sure, I guess if you have, say, Quantum Fireball 540T and its SCSI twin just lying around and you don't mind losing both of them I'd love to hear what happens. But ultimately this isn't a very scalable solution. (While the IDE versions of various drives that have SCSI twins may well of sold in larger numbers back in the day they're not going to be much easier to find today, and there's no reason to think their mechanisms were any more reliable.)
I never bothered with mine because on top of the PCI bandwidth limitations (which are extremely harsh on the B&W, the "northbridge/southbridge" pipe on that machine is just a 66mhz 32 bit PCI bus; the video slot alone can theoretically completely saturate it) my B&W's "Upgraded" (sidegraded?) video card is a Radeon 7000. Sure, it's Quartz Extreme compliant in that it supports arbitrary-sized textures, but, well, in OpenGL it squeaks out being about, I dunno, 60% faster than the original Rage 128 on a good day? Definitely nothing to write home about.
For a while I *was* holding onto a dual-port FX5200 PCI I scavenged out of an old Dell Precision (it'd been set up to drive four monitors) with thoughts of trying the Core Image experiment, but I never got around to it. The B&W (well, Yikes, effectively, since I have a G4 ZIF) doesn't run the shipping version of Leopard anyway, and while Core Image did *exist* in Tiger it wasn't really used much.
Yes. The Apple branding isn't the important part here. At all. It would behave just like the one you already tried, technically bootable but the code which drives the "C held down" function has no idea to look for it where it is.