P38 Engine Swap What can Fit

hi guys i got a few problems with my current engine not starting up or driving on petrol i have spent a lot of time and money and cant seem to get it working

i was wondering which other engines can fit in to a P38 mines is a 4.6 gems engine and which would be better

i did see a range rover p38 a while back with a bmw alpina engine fitted looked good and was quite powerful