Spesh - The M1 was available in white with black accessories and originally came with steel pro-class rims so i would say it's pretty faithful as it is - without being pedantic about the wheels you'd only have to change the decals (Del ?) and the pads (Firebird ?) and she'd be right as rain
Thing is ... the newer decal that you'd need was red lettering so it might fudge up your gold look, which i reckon looks nice as it bounces nicely off the cali lettering.
If you were at the begining of the build i'd say go M1, but since she's built and looks sweet as..... i'd leave her as is
PS - as a full bike with the OE skyways i reckon 160 quid was'nt that bad for that ebay bike