I often apply a little brake while coasting downhill and use the same rigjt foot to apply just enough throttle to limit the pops and crackles from exhaust and this is considerably easier now with the firmer pedal.
I used a 7/8" ba astina master cylinder due to its brake line port design and shorter length than other Mazda masters. It shares the same design as early nb masters where a larger diameter rear extension with o ring seal fits into the booster and has the extended pushrod mounting tube.

Nb, ba astina (97 4cyl, non abs), na6 masters left to right respectively.

Boosters for the different models.
I have numerous master mount plates available as the lazer cutters required minimum order amounts of ten.
The bore size suits the nb style master rear diameter however the smaller rear diameter of na6 master will fit with room to spare.
I am running NA8 front brakes with bendix road pads and NA6 rear rotor and pad sizes for the moment with wilwood proportioning valve adjusted to suit. A move to larger rear rotors is being considered to compare performance if not only because they are on hand in my shed to fit.
I used an old transmission bellhousing bolt to fab a new pushrod, cutting the head off and rounding the end on a drill press with files. A small bush approximately 15mm long and turned to a tight fitting diameter was first installed within the rear master pushrod tube receptacle to prevent the pushrod fouling when swinging through it's arc between pedal limits. There is a possibility to raise the pushrod- pedal mounting point higher than the 20mm increase as on my pedal arm that would reduce pedal effort further. Using a smaller 13/16" master is possible also.

It all started with a purchase of a booster delete kit from chase bays that was frown upon by our Christmas holiday hosts and led to thorough research of a suitable design using factory components.
A big thankyou to those who provided their time in helping me with the design.
Overall very happy with the improvements to braking performance.