for the BEST brakes upgrade on a 1200, look in ca18det_man's photo album

but there are many good brake upgrades that can be done easier onto maybe datsun/nissan struts

a few to choose from
stanza 200b or 240k struts
-sumitomo twin piston calipers with 240k or 200b slotted rotors(good for A series )
-landcruiser or hilux calipers and either verada or camry discs depending on caliper
-maddat rx7 brake upgrade, see 4nik8's photos
-r32 or z32 calipers on custom mounting bracket and r32 gtst?? discs, see ca18det_mans photos

180b struts
-verada discs and v8 commodore calipers, or possibally volvo calipers for 4 piston caliper

R31 struts
-r32 calipers with adaptor to fit the strut?? with standard disc

cant think of any more off the top of my head, and details or each are a bit sketchy so you will have to do a more detailed seach on the chosen conversion