Guidance on selling a A4000 and A3000

[SnkBitten]

Might be a bit of an inconvenience but do you have a way to attach the Amiga HD to your PC and use WinUAE to boot the drive.  You can then set the screenmode to DblNTSC or Multiscan and save it and then reinstall the HD in the Amiga and boot to a screenmode a standard monitor can display.  I had to do similar actions as I have no 15Khz monitor for my A4000 and it arrived with no HD and I had to install the OS in WinUAE and then move the drive over to my A4000.

[SnkBitten]

If I can use WinUAE to make a working IDE drive and then just drop it into the 4000 that would be perfect. I've never used WinUAE though so it would be a learning experience.

 
This is exactly what I had to do.  I had a blank IDE HD, no 15Khz monitor and a bad 3.1 Install floppy.  I purchased a cheap IDE/SATA to USB cable with power supply that allowed me to plug in the IDE drive to a USB port on my primary PC (no IDE, it's all SATA internally).   Configured a WinUAE setup to emulate a basic A4000 (but with JIT and Fastest possible checked) and added the HD "Add Hard Drive" and configured it as A4000 IDE unit 0.  Got 3.1 installed, IDEfix97 for my CDrom and then installed OS 3.9.

I keep that configuration around as I've done a few things that screwed up the boot and had to move the drive back from my A4000 to WinUAE to make corrections.  Relying on DblNTSC/PAL or Multiscan is a pain if the boot doesn't go smoothly as you see no error messages, requestors, etc...to know what's going on.