You can find general information for the Honeywell 200 just by searching the Internet but for more technical information the following two documents on the Bitsavers website are extremely useful.
For the internal electronics see the Series 200 201 CP Logic Training Manual (PDF 9.7 MBytes)
For a description of the machine's architecture and instruction set see the Series 200 Programmers' Reference Manual (PDF 21 MBytes)
Also a more general decription of the machine and peripherals is in the Honeywell 200 Summary Description (PDF 5.1 MBytes)
Apart from online documentation I discovered some useful Honeywell technical reference manuals in the ICL archive held by our national Science Museum in London. The archive isn't in London though; it's in a special storage facility on a disused airfield at a remote rural location, so I've only been there once so far.
The best colour images of a Honeywell 200 in operation actually appear to be in the 1967 MGM film Billion Dollar Brain starring Michael Caine as mentioned on the Starring The Computer website. Relevant extracts from the film may also be found by searching the Internet.
In 2014 I wrote an article entitled "The HoneyPi Project - A Home-brew Computer with Attitude" about the background to the project, which appeared in issue number 66 of Resurrection, the journal of the Computer Conservation Society, which actually specialises in the conservation of British computers here in the UK.
Ongoing discussion of this project can be found on the thread Honeywell 200 Resurrection in the Vintage Computer Federation Forums website in the USA.
If you are interested enough in the project to comment or can contribute to it in any way then you can contact me directly by email as "rob.s" at this site or indirectly through the Vintage Computer Federation website mentioned above as "RobS".