oh man i love those old datsuns! that would be an awesome project! i would be interested in seeing some of your non-eco projects too... i've been involved in some cool resto - mods too.
for your project i would whole-heartedly recommend a cool turbo diesel if you can get your hands on one... they are all over the place in central america on small pickups and suvs. also the nissan frontier came with a killer turbo diesel in other countries...
JDM Engine Corp Engine Details - Nissan Frontier YD25DDTi Turbo Diesel Engine YD25 Neo