Heaviest Headshell?

I know but not enough weight. I have 3 quarters sitting on the headshell now which is like 18g with the Blu Tak. I'd like a more permanent solution. 

Lead weights, like the ones used to balance wheels.

Certain FR headshells can exceed 20g easily. You’ve glued 3 quarters to a 20g Ikeda? What cartridge?

No the quarters are on an sme headshell. The cartridge is a Decca London Super Gold. 

I am using an Ortofon LH 9000 headshell with my Koetsu Urushi. The headshell weighs 18 g. But it costs a lot less than $300. To that you could always add more weight by various methods as you know. Your cartridge must be remarkably low in compliance.