87 Ramcharger ignition questions

Ok, so I bought a Ramcharger a few months go and I was thinking of upgrading/updating the ignition on it. I believe it has some sort of lean burn system behind the battery, in the fender. I was thinking of converting it to a HEI system with a new E-coil, a design2drive conversion plate and HEI module, and a MP quick advance distriburor.
Can I just change the coil and distributor and leave the wires connected to the lean burn system? The dist in the truck now does not have any vacuum advance or any mechanical advance in the distributor. I presume the big module controls all of that somehow and I think, in my mind , that a quick advance dist, HEI, and vacuum will get me better performance and fuel economy. Am I on the right track?