Saw this tank on gumtree a while back, good buy.
The plumbing should not to too hard to implement yourself with some planning and the right selection of parts.
Personally, I would avoid using substandard Bunnings/retic style PVC setups, seen tanks done like this before and are rarely a close to professional job.
For me personally, buying initially cheap and nasty fittings is false economy. A plumbing failure on a larger aquarium can mean potentially thousands of dollars in damage when weighted against a few dollars extra on a fitting.
I generally stick to the better quality injection moulded fittings, most of which are self-sealing such as HANSEN.
Also on the note of valves, I strongly suggest avoiding the traditional PVC 'red Tap' valves. The rubber seals on these values/taps offer appalling long term performance, usually getting stuck.I would opt for better quality Philmac (have a better quality O-Ring/mechanism of action) or better yet, just use large 'green top' mechanical valves. They offer much better value and always work smoothly.
Plumbing of a tank this size will be not cheap given the holes are 32mm. This means they will house a 32mm flange. To give an idea of cost, a Hansen 30mm flange is roughly $40. Just to put flanges on the tank would be 5x $40 = $200.
I think a ball park of $300 to $400 worth quality fitting will see it all plumbed up nicely.Tank plumbing is one of those things, do it right, do it once, it's an absolute PITA to do it again.
That have being said, the design of your plumbing depends on many variables.
What kind of filter will you be using (Sump/canister)?
If sump, How big?
What kind of pump, how many litres per hour?
How many outlets would you like?
Where do you want those outlets positioned?
What do you plan to keep?
What other equipment are you using ? (Inline heaters ? CO2 injection?)
Just consider that once you factor in all the extra plumbing for a sump + Building the sump + Filter media + Return pump, you are pretty much at the same price point (If not greater) than employing 2 larger canister filters. If it’s just for freshwater application, 2 large canisters would perform well. This means you can block off that silly overflow box and not have to purchase 5 extra flanges…. For canisters, just 2 inlets, 2 outlets for 2 filters. A dolphin 2400 canister would be ideal.
Aquotix has a single Dophin on there 8x30x30 Cichlid, a similar size in volume to your 1270L tank.