has anybody done the upgrade to electric over hydraulics to their drum surge brakes? What actuator did you use and where did you mount everything?

Not to drum brakes, but have installed on disc brakes with surge. I'd suggest you do a disc brake conversion, and install the EOH. You won't regret doing both.

I remember something about the PSI being lower for drum than for disc. If so, the actuator for one may not work for the other. If you are thinking of upgrading in stages.

Yes, I believe Chart is correct the actuator for drum brakes, I think is about 1,000 PSI and for Discs, 1,600 PSI. Price about 500-700 dollars and include breakaway kit, another 40 dollars.

I converted my surge drum brakes to EOH several years ago. They work great! I used the Dexter 1,000 PSI unit. Very easy to install