To use it for the most widely accepted scale for R2 Builders (IMHO) it's too short and not wide enough.
It needs to be 46.5cm x 30cm, but it's 45cm x 22cm
While it does need a straight start before the curve starts (the rings) adding 8cm will be too much to get it to 30cm and it sides would need padding out by at least 10mm.
Of course the R2 body could be scaled down to compensate, just depends on what level of screen accuracy you're chasing.
I've bought a completed screen accurate (headless) R2 from a past member, so I find the search for a non manufactured dome interesting.
Good find though:cool
Rogue