Body bends when jacking

well just got the K out, think im screwed, gonna need to find a new one..or put the k from the donor 71 i have...this one looks beat to hell, plate where steering pump bolted to is cracked and welded right over, looks like the area under the tbar adjuster on driver side took a hit and is bent, and I dunno what factor welds looked like, but these look like ****, bad beads, splatter that still chips off...and even a spot that is burned thru.

gonna upload pics, u tell me.

If i need a new K, will the 71 bolt in for me? im assuming they are same bolt holes..
I have a 73, so i got discs stock...ulitmately i want the viper calipers that require a 73-76 drum spindle, and i am gonna be putting in a crate 360 or higher....im assuming motormounts are different and can be found to make whatever fit.

any other differences i need to know? mind you i just bought a pst rebuild kit for 73...