firewall differences from linkage to cable.

[ghetto_superman]

so im smoothing the firewall on my 68 with a throttle linkage.. im not a big fan of the linkages and would like to change it to a cable.. i realize theres a thread on it, but thats just retrofitting and fabbing a cable to fit more or less... i was wondering if it would even be feasible to cut a chunk of a cable firewall out and weld it in to mine.. or if mine already has the necesarry mounting points.. i just have to open them up... it would also help me if anyone posted pics of their smooth looking cable setup.
also i know that 71-72 comes standard with cable, but was it availavle on 69-70? (ill be getting a parts truck soon and i think its a 69-70)

thanks for all the help!
-Mike