I would like to share some things worth consideration also......
If you have fitted a master cylinder off a different model, never mind the reservoirs and pipes being back to front, but also bear in mind that diameters may be different between models or break points in production also. Did you over haul your front calipers and replace the pistons? We went bonkers once with an XC ford until we discovered the new pistons were concaved, and the old ones were flat. subsequent lunch room raves over the years also had comparable things like that with holdens, just as suppliers like Repco were becoming involved with replacement brake parts. Another thing to t is the bleeding technique, where you have an assistant pump the pedal vigourously and then have them count 1! 2! and on three,snap open the bleeder before they stomp hard on the pedal. This can often dislodge air pockets in some systems. All other advice offered by other members has been good too, assuming you have adequate knowledge on brake systems fundamentals. as a matter of course, did you bleed the new master on the bench before installation? This too can cause hours of needless fun. A messy job, so do it well away from any vehicles. I don't mean to sound condesending, but sometimes the most simple things may be the cause. I hope this helps too.

--- Updated ---

BTW are you anywhere near Sydney? I can give you the name of an absolute guru as far as things with brakes, clutches and heads go......