Brake improvements

[Clara]

Now aside from fitting a servo, anchor, and three parachutes to ones HA (1963 deluxe) what other mods are there to improve the brakes?

I assume that the van would have had better brakes (or at least hoped considering these were still around in the 80s) - is it possible to do a straight swap of the rear end (drums)? How easily available are these parts at any rate?

What mods have people done to the braking system when they've fitted, for instance, a better bigger engine? (Not something I'm considering doing for a while yet). Are there any calipers that will fit on the front end that don't require too much modification?

Thanks.