The lowers you see with the pins are the push pin lowers. You can get "clipped and pinned" lowers that will fit the semi auto shelf receivers like the CA89 you have.
Adam Webber from HKparts has a bunch for sale in the HK acessories forum: http://hkpro.com/forum/showthread.php?t=73159
Adam Webber from HKparts has a bunch for sale in the HK acessories forum: http://hkpro.com/forum/showthread.php?t=73159