Provided the base machine is fairly light, and has the 5600lb MTOW increase then you can carry quite a bit of load. A machine on straight floats is around 1600kgs empty and with the mod can takeoff just under 2500kgs.
For amphibs you are looking at another 260kgs (minimum) to your empty weight over the straight floats.
Not to sure what the aircraft is without floats...anyone have any idea?
Specs say empty weight of 3,000 lb (1,361 kg)
With the upgrade kit with a max weight of 5600lb (2,540kg)
Gives 1179kg without fuel.. Even with 400L (~300kg) fuel onboard, gives a useful load of 879kg..
I'm not sure if the Cleveland wheels change the weight much over the Goodyear when you fit the upgrade kit for wheels, but todays instruments, radios, starters & alternators are all lighter than was factory fitted back when the machines were built, so even with the 'upgrades' i'd imagine the weights would be fairly similar...
Biggest issue is keeping the thing within CoG when using an extended cabin without spending the extra $$ fitting the engine mount extension kit...