M13A to M16A swap: Would you be worried putting this donor engine in?

I'm currently swapping my Jimny’s high-mileage M13A for an M16A out of a Suzuki Liana.Both engines from 2003, the Liana engine is supposed to have only 102,000 km (63k miles) on it, while my original M13A has done 250,000 km (155k miles). However, after pulling both valve covers, the contrast is making me second-guess things but i'm not sure if this is a problem or not.How concerned would you be about dropping this M16A in? Is this anything to be worried about?Also the knock sensor on the liana had been slightly leaking/melting did this engine maybe run hot or something or is that something that just happens? i put a picture of both knock sensors to compare. The one from the m13a is also a bit sticky and soft, is that normal?And the 3 passages on the left side of the cover, what are these for? because there is alot of crap in it in the clean cover from the m13a but surprisingly the ones from the dirty m16a are way cleaner.Thanks!

the reason for the darker stained is no regular oil changes and a old oil sitting around ie not running, happens a lot on old low mileage cars, my celica from 1990 is on 200k odd miles and the engines is super clean but I do oil changes every 5k or every year is I drive less than 5k.

after fitting it I would run the engine for like 100 miles and do another oil change just so it cleans if there is any oil gunk in it.

Not great these stains but not too bad either. The m13 and 16 most often just run and run anyways.
The three holes are for dipsticks? one drilled in the top and the others not depending on engine type. Not much flow there to flush out old gunk. The m16 might have better flow around there in this case.

Thanks for your replies,

So after inspecting the engine a little more, other than the darker color it seems perfectly fine from what i can see.
All valves are still within spec, cilinders look great as far as i can tell and engine turns around fine by hand. 

Meanwhile the m13a has 11 valves out of spec and looks a little dirtier in the bottom end.
 
I guess i shouldn't worry so much about the color   i'm going to put it in and drive for a few months then change oil hopefully it will clean it up a bit.

Any thoughts on the knock sensor? i'm putting in a new one anyway just to be sure, but i'm wondering why does it leak like that.

I might make a project post if anyone is interested since i'm doing a complete body off rebuild, almost finished already but i still got the pictures!

Wynn's engine flush or a cupful of diesel and then warm the engine before changing the oil, get rid of any sludge potential.