If you've done the obvious things like changing the fluid if it's old (it's hygroscopic and absorbs atmospheric moisture), and bleeding the system, the next thing is to check the booster. Is the diaphragm OK? Is there a vacuum leak? When it's safe to do so while driving, switch off the motor and apply brakes briefly at intervals ..... you should get at least 3 to 5 brake applications before the vacuum reservoir is depleted and the pedal feels hard with little braking. Check all the connections on the vacuum line to the booster. Another thing to check is the little non-return valve on the vacuum pipe that it's working properly, then about a minute after switching off the motor while stationary, pull the vacuum pipe off the booster ..... you should get a sound of the vacuum being broken. A point of interest here, if you have a vacuum operated diff lock, the take-off is on the booster line and the servo could also be leaking. A common setup is to have the difflock vacuum take-off positioned after the non return valve ..... change it to before the non return valve or put a second one in the line after the take-off.
Then as mentioned, do not underestimate the leverage that bigger tyres have over the braking system .... bigger tyres means poorer braking. Another thing is the compound of the brake pad linings .... a hard lining will last longer but gives poorer brake performance. Ferodo pads are soft and work well .... ATE are a fraction harder .... both are quality pads, but I would definitely fit Ferodo with the bigger tyres. The braided hoses are a plus and will help, especially if the non braided ones are old.
If all this fails, you might have to look at upgrading the master cylinder.
Hope this helps.
