Upgrading a 400efi to 500

I believe the main obstacle is the crank and rod: the 400 is shorter stroke but has the same bore as the 500 (someone might correct me on that) so you’d need to shorten (machine down) the barrel which would then need a shorter cam chain. And so on…
Alternatively, buy a 500 engine and stick an injector body on it?? You’d probably have to replace the injector with an XT660 unit as I’ve read elsewhere cos the stock unit isn’t up to it.
Over simplistic perhaps but, it’d be a bit less trouble and then I guess, also less fun for those so inclined…