elliptical function highpass IS a fairly standard one to use.
but at least ONE of your poles is WAY mistuned.
i woud open ciruict two of the elliptical poles (unsolder the capacitor to them), meausre the response on the network analyzer, then go to your simulator, open thos same capacitors, and compare the two responses. IF the tested circuit pole frequency is off, adjust the component values until it is right on the money.
you might need to parallel up two capacitors to form the one value you need. for instance instead of using 1.2 pf, use two caps 0.2 pf in parallel with 1.0 pf. that way you can move the smaller cap up and down in value in -.1 pf steps.
when that one pole is tuned up, reconnect a 2nd pole and do it all over again. and so on.
For these type of filters to work well, you need to select the highest Q for each component that you can find. Getting the high Q inductors is usually the issue--you might need to switch to tiny air coils