do you need uprated brakes for travelling at that speed? say 60+ mph, i would imagine stopping quickly with ordinary series brakes would be interesting
that's a can of worms
my 109 has it's original brakes as supplied without a servo and single line and weighs a couple of cwt more than my 88", it stops reasonably well and definitely up to mot standards, you just have to press on the pedal hard as it has no assistance
my 88" originally had single line brakes, no servo and 10" single leading shoes all round, that system stopped it well (so well it would at least go very light on the rear and squirm) but again you had to press on the pedal hard
i've since tinkered with my 88" and fitted 11" rear drums on my front axle, these are still single leading shoes but obviously a bigger diameter (plus wider), i've also fitted a servo assisted dual line braking system (minus the PDWA), the brakes on this one now are very light and with little effort i can have the vehicle squirming under heavy braking
where brake upgrades are concerned there's quite a few things to consider and to experiment just for the sake of it can be fun (but expensive especially if you get it wrong), which was the reason i put the bigger drums on my 88" (the downside of these is i believe they take longer to dry after wading) a bonus i found using these is less often underneath having to adjust them plus there's an adjuster on each shoe (4 adjusters on the front axle now) so pedal travel can be minimised really easily
now there's disc brakes (two or three different kits can be got) that can be fitted to all four corners or just the front axle depending on how big your pockets are (you may need an upgraded/assisted mastercylinder and pedal box)
the benefits of these is/are, they dry really quickly after wading, no more crawling underneath adjusting them, no taking drums off after playing in deep mud to clean them out, no wondering which way the steering might snatch after having been laid up for a couple of weeks (sometimes less and as long as your steering components are in good condition), less pedal travel if correctly set up to begin with, easier to change pads than shoes, less risk of fade (i've not had that with my drumbrakes to date but i do think ahead and select the correct gear, keep my gap and speed appropriate to the terrain)
there's bound to be another couple of benefits that i haven't thought of
like i said it's a can of worms, i know plenty of folks that drive thier Series with V8 motors, 200/300tdi's, a couple with tuned 2.25s along with the ones that have the original engines under thier bonnets (most of them don't hang about either) and the majority still have the "as fitted" by the factory standard braking systems
there will be differing opinions as to what is needed, what can be improved and what folks desire
i've a spare can here, anyone want to open it ??