Frame 12 ,MK IX Spitfire

I have been asked for: a. the inside heighth from the Datum to the top of frame 12 in a High Back MK IX spitfire b. the inside width of frame 12 at the datum point? I am involved with the restoration of a MK IX but available drawings are not detailed enough and I am not able to crawl into the fuse to take measurements. Anyone able to help. I think the original questionner may be a modeler. Thanks in advance.