A330/340 are far to large. Flew with a bofin once who was convinced we should have brought some more Tristars to use as MPA, on paper it could fly further, longer, higher, faster, carry much more, etc. 4 hours at low level on HISS and ASW finally convinced him that maybe his plan was flawed
For a long range MPA 4 engines please, 75% is much better than 50% in the event of loosing a donk although I'm sure someone will argue that 4 engines gives twice the probability of a failure compared to 2 engines
