Catalunya 051

I have a bayonnet cap on my Scoob brake master cylinder and I want to get an EZbleed kit but apparently they don't do a bayonnet cap fitting! Any ideas, do I have to drill the OE cap and then block the hole afterwards? I would rather get a surrogate cap from somewhere but would like it to be cheap (and I must have it this weekend too, as I have been waiting for weeks to get the 4 pots on).