If I was serious about getting far from home >300-400mi with an aftermarket EFI, I would consider carrying a spare unit. As costly as it seems, you're up a creek if you do have an issue and nobody will have parts on-hand to get you going again.

My Hemi swap isn't really in much better shape from that aspect, but I do have many factory Mopar quality parts on it. That said, I have about 5,000 trouble free miles on it.