Ok here goes.
My short Getrag box, from the front face, with bell removed, to the tip of the rear shaft is 42cm
Mine is a LHD, therefor I have a throttle cross over shaft, as well as a brake pipe and the main wiring harness, between the engine and the firewall, which makes it difficult to get in there, in order to measure correctly. It looks like about 2cm, maybe a bit less. The rear of the tappet cover, at the top, is approximately 10 to 15 mm from the bonnet latch housing. My engine sits at 2 to 3* nose up.
Please let me know if you need more measurements.
Regards
Chris
Ps. I have a pit in my garage, if you require measurements from below.