Bandit 600 and 1200 New Project - Questions-feedback

[sunnyorlando]

Hi all..
I'm working on my 3rd Bandit 1200 rebuild, though this one issue I've not had to deal with before - front end damage.
My most recent was a '99 Black 1200 that turned out to be an awesome beast and runs great. The prior was a red '00 which also turned out great and sold it a while back.
Now onto another ’99 but this one is a blue 600. From the steering neck back it's in excellent condition with only 7500 mi. It was garage kept and well taken care of.
On this one, it was a front end crash so the forks are destroyed - at least the tubes are, and I'm not sure if the bottoms are reusable. The fairing also destroyed, but that OK as I'll turn it into a naked anyway. The bottoms are not directly impacted and the tubes severed at the bottom triple tree section. The triple tree appears in good condition and no damage to the frame. It steers freely with no play or catching. The stops are intact.
I know from past rebuild experience that many parts are interchangeable with other similar models such as some GSXRs. The 600 has 41mm tubes and the 1200 are 43mm so a direct tube swap will not work. I may have to go with a full tree and forks of a 1200 if I cant find a set of tubes for the 600. Any fitment compatibility issues with dropping in a set 0f 1200 forks? Any others that I may look for that are compatible without having to modify the tree? I've read/seen some that can be modified to fit, but I dont want to get into that one.
I'm looking to learn what front end components I can consider as replacements for this front end.

Also - any thoughts on transferring my awesome ’99 1200 engine onto this otherwise almost perfect beautiful blue bike? I ask ask this as an option to maybe make my black 1200 become a donor as it is complete, it just not as clean looking.
At a glance it appears to drop right in, and just change the ECU. Is this correct?

Thanks!