Some of the best in my opinion, poly in oil, maybe somehow similar to ASC.
https://www.tdk-electronics.tdk.com/inf/20/50/db/power_99/01280167.pdfI think they would be great in a Big Boys tube project
https://www.tdk-electronics.tdk.com/inf/20/50/db/power_99/01280167.pdfI think they would be great in a Big Boys tube project