Your '72 was the first year for a front disc set-up and it's rather unique, different from all the later ones. The later ones, and most discs for that matter, bolt to the hub. Your '72 isn't like that. The disc carrier has tabs on it that fit into slots on the hub. I'm not aware of any aftermarket replacement discs for this one year only set-up. Your only option may be to drill the one you've got.
And speaking of drilling the disc, I've done 3 or 4 and didn't find it all that difficult. I did them all on my $49 HF benchtop drill press. For drill bits, I didn't use anything special, just a good quality high speed steel American made bit. After center-punching the pattern onto the disc, I "dimple" each punch mark dry to get the hole started and centered, then add a drop of oil and drill it through. The disc material didn't seem particularly hard or harder than most other steels I've drilled through.