Engine and Transmission Tech

my dad is about to give me his old 93 range rover classic (4.2) so that i have something to tow my race car with. problem is that it's been in a barn somewhere for a couple of years because it just won't run properly. I have a few ideas for the cause but in case I lose my sanity and do not get it sorted, i'm thinking about backup plans.

I was at the local scrapyard the other day and noticed that there's a 2000 land rover discovery 4.6 there. the prices at this yard are quite good. question is, can I run the 4.2 on the bosch management designed for the 4.6? what would i need? from what I estimate, the swap wouldn't cost more than $200...but that's based on guessing the complonents required, i may need more of course.

at the moment i believe i would need:

the ecu and harness
maybe it's interface with the cluster and possibly the cluster?
all the sensors
post cat o2 sensors
maybe the intake manifold and plumbing?

am i mising something in that list? will the motronic system say wtf to the smaller engine?

thanks

From recolection, the 4.6 also has coil packs and igniytion pickup. the 4.2 uses a traditional distributor
Regards
Tony