Hi Andy,
KSC2056 in an NPN medium power device, good for up to 800V, perfect for Q2 I would think.
I think I sent some 43V zeners, you could try one (or more as required) in series with the current source so reduce the voltage/power stress. I don't recall the power rating but the look like it must be more than 10mA will make (~0.5W?). A little bit of space round the zener will needed
dc