Greetings all
I need the hive mind please.
UK based (Birmingham)
2008 XF 2.7 V6 (X250 I believe)
49000 miles on it, verified from the MOT history

Bought the car 2 years ago with an engine knock. Had the lump out after checking other things first (hoping it might have been an injector knock), turns out the crank bearings had spun.
Crank shot, block shot.
No one would line bore the block if I supplied a new crank so I had to replace the engine. Got one of those from a written off 2008 model.
HOWEVER...........this is where I screwed up.
Removing the engine means taking off the scuttle panel and associated plastic bits underneath the screen to get at the wiring harness multiplugs, 3 of which go into the PCM/ECU under the screen.
If you happen to (as I did) leave the PCM/ECU in place and DON'T replace the scuttle panel/plastic bits, when you leave the car outside for month's, rain pours down the screen and goes straight into the PCM/ECU AND FLOODS IT!!!!
This i found out the hard way as it was months between getting the replacement engine and me doing the job.
So I sourced another unit from a 2009 model, discovered it's not exactly plug and play so here's where the fun begins.......Re-programming........

I have SDD and a mongoose cable, can't remember what version it is, but is there a sequence that needs to be followed with the programming of different modules through the car?
I know I have to try and do the clocks, TCM, key fobs, security system, what about mileage correction as well?
From what I recall the cars mileage is also stored in the PCM and if it doesn't match the displayed mileage it wouldn't continue the programming? Is this correct or am I barking mad........
What else should I do please?
Hoping the hive can help as it's a beautiful low mileage example that should do me for the next 10 years at least (barring dipshits with no insurance)

Thanks in advance