I haven't found a photo of a radar equipped Blenheim IV to actually see the configuration. Everything I've seen for the MK I has an AI Mk.III set up, which is the same as the Blenheim IVF had. The antenna I have available (built for a Mossie NF.II conversion I think) are an AI Mk.IV. I can fit these to it in a pseudo Mk.III configuration, unless someone could whip up a set of AI Mk.III antenna.

(I don't mind going through the mess of getting them to stick to the right spots on the plane if someone does the models).
EDIT: There are some diagrams that might be useful in the threads James posted.