Z50 2s are hardtail Z50
655a is early Softail Z50
HT7A is CT70 HK0
594A is CT70 HK1
533A is CT70 K1-2-3-4..?
For the others...I'd Google those numbers, and search them on eBay, etc. Also look for them in the clymers. I think maybe ATC 70. ST50 or 70. And I think the 20A might be later model CT70's and many other 70cc bikes.