79-89

Ok....
Heres the deal...
I have a 79 xj-s V-12 with a rebuilt engine, less then 10K miles on it... runs and drives great... electrics are very flaky, as well as some other things...

I also have a 89 that all except the engine are exceptional, including a brand new trans.

Swap the 79 engine into the 89? (89 has marrelli ignition)
Any problems anyone can foresee?
I do have to do emmisions testing here.....

any thoughts?

Thanks
Patrick