[Scribus] need to create greyscale PDF/X-3

[Nik]

Hi Folks,

My apologies if this has been covered already in FAQs or the like, but 
my searches have not found any direct references.

(I am using the standard scribus 1.2.4.1 as maintained in the Fedora 
Core YUM repository.)

I have a scribus document (a newsletter) from which I need to produce 
multiple output documents: a colour PDF for a webpage, and a PDF to send 
to a printing house for monochrome printing.

I have assembled a 4 page test document, generated a test PDF/X-3, and 
sent this to our printers. They have responded that there are a few 
minor changes needed for them to be able to print from this:

1. All pictures need to be in greyscale

2. If we are printing in monochrome (which we currently do) then all 
text must be black.

3. If we are printing in black plus one colour (which we don't currently 
do, but are considering the option), then we need to provide the 
document in black plus one colour expressed as a Spot colour.

In addition, the document has fill colour in some of the boxes 
(specified as red @ 15%). I presume I need to output this as black @ 15% 
for the monochrome output.

I had hoped that I could produce both PDFs from the same document - ie, 
be able to specify greyscale for images and black for text/stroke/fill 
when creating the PDF/X-3 for the printer, and specifying full colour 
when creating the PDF for the web.

Q1: Is this simply a matter of my correctly setting some output 
parameter(s) that I haven't fully understood? For example, installing a 
greyscale Output Profile (instead of the default Fogra27L CMYK profile), 
or possibly an ICC colour profile?

Q2: Or do I need to create a separate greyscale document, either 
manually, or through a script or plugin?

Q3: Is there some other way that I haven't thought of?

All comments and feedback gratefully accepted.

Cheers!
Nik.