import engine for a 50's ford

I at the point were I could either do up the flathead in my 51 merc pickup 
or swap a new model engine.  If I go with a new engine I think I'll go
with 
an import like a toyota.  I know I know, blasphemy.  But I think they are 
generally more effecient and last longer.   Anyone know of a suitable
import 
that would do well in a truck of this weight?