Testing caps (fwd)

I posted a message a few weeks ago about some oil-filled 10nF 80kvdc "xray machine" caps I have, asking if they might be suitable for TC use. Several people thought it was worth a try, but suggested a safety enclosure, in case they overheated and exploded. My question is this:
Is there a way I can test them for suitability before building the whole system? I have a NST, and could fashion a temporary spark gap. I'd like to run a minimal system long enough to give me confidence that these caps will survive before going any further, as I'm not interested in rolling my own cap.
Two other questions:
I had hoped to use 10" diam acrylic tubing for the secondary, but at $40/ft, may have to use PVC. But I'm considering getting some sheet acrylic and melting it around a form, possibly in half-cylinder sections, then cementing them together. I've been pretty successful forming plexiglas in this way in the past, and assume that it is the material of choice. Has anyone tried this? (I'm assuming that the sheet stock is much less expensive.)
Finally, I think I read that if the spark gap is close enough to the transformer, secondary RF suppression isn't necessary. Is there agreement on this?
Thanks for your comments.
Terry Perdue