Some Hammerheads and also early Dazons used this type of 4 link rear suspension. It was dubbed the "Dog bone suspension". It's strong and gives smooth swing arm travel. The ride is more cushy too but like you found out, it's possible with longer travel shock for that dog bone link to over articulate.
Limiting straps are your best bet. There's some good info here
http://www.filthymotorsports.com/Lim...limitstrap.htm