Hi Wayne,
Check this from Ohmite International - Audio Gold Resistors.
They have non-inductive versions available. "Specifically designed for high-end loudspeaker and amplifier applications" as from their website. Isn't life beautiful? They have a lot of different models including the 89 Series N (Non-Inductive 50W) and the HSN (Non-Inductive 100/250W).
The Audio Golds are 3 to 50W.
You have to check your area representatives for orders.
Did you find the Wima Caps MKP4 of any use? Do they sell them in small quantities?
Best Regards