You would need a cable conversion. The efs Hondas had a cable trans and the eg ek had a hydro trans. it's not that hard. You could do a whole honda swap engine and trans would be a ton easier than a diesel.
Thanks, what engine/trans combo would be the optimal in terms of rpm and fuel effeciency? Currently my ef's are turning around 3600 rpm at 75mph and I want to drop it down to 2800 (DX gearing) or so to improve mileage and also decrease the noise of that screaming engine. There must be an optimal combo which would give happy rpms and also improved gas mileage.
I love the idea of the project and had a great suggestion for a motor, "but" then it hit me, and please correct me if I'm wrong here but I'm convinced that your year Honda falls into the generation of the reverse rotation motors.
I was going to recommend a Yanmar 3cylinder diesel they use in HD lawn tractors (golf course, grounds keeping and cemetery use mostly) They only make about 45 HP but they knock down nearly 100 Ft lbs of TQ slightly off idle to about a 3800 redline.
Another, pricier route, is to look into importing engine. Japanese emission and taxing laws means there is a fairly quick turnover for vehicles. It is possible to import the used engines, and some people do to get performance ones for their Civics.
Honda makes diesels for the overseas markets, and they have a good rep. I have no idea if importing one of the diesels would be possible, or if our emission regulations prevent it.