The rods are different width because of the split crank throws required by the even firing order V6 it makes them thinner.

Mabey a small TBI (4.3 or 305 Chevy system or holley)could be easily tuned to run it. I think that tbi may be the best way because the fuel would have more chance to evaporate in the manifold before going in the chamber. It would also run better cold, not like I have a problem getting a carb to run cold but I may have to consider this even if I stick with the 273.