Compaired to a dead stock early 80's ke70 with a repo happy -spec 4k ->
7K is wider, the motor fits.. but it doesn't fit totally snug. needs a small amount of massaging.
Sump needs to be modified.
Standard gearbox isn't going to last too long behind a 7k. Or the diff either.
So then theres gearbox upgrade, which is normally hydraulic. And the custom tailshaft & gearbox cross member.
Which means the gearstick doesnt line up and the tranny hole needs to be changed, which means the interiour has to be changed, and the plastic surrounds need to be modified to make it look stock. Which means the gearstick has to be bent to obtain standard ergonomics.
And the speedo cable to suit. Ae71 pedal box job with custom hydraulics. And the wiring connector differences.
And then the exhaust size, and the angle of it. And the 4k starter motor wont last very long on a 7k. Or theres the fact that the dizzy system is different.
I suppose then there is the different sized radiator fan, different pully setup, different belt size, which hits the standard shroud, which no longer fits, which means you need electronic fan. Which means you need to have a coolant sensor and wire that up. Which means you need to re-rout emitions for the hole the temp sensor now takes up. Which means you need to know what your doing with lots of spag-bowl lines.
Then theres the fact that a standard 7k radiator is 3 times the size of a ke70 one. And considering a 4k got hot with an ADM radiator from new..
Oh, and then theres. Ill stop now.
Sure none of these things are massively hard to do in the sceme of things.. But its not a throw in 1 day bolt in job. That is, if you intend on doing it properly.