The only problem with the Denso swap is the regulator is built into the PCM on them. I don't know what it would take to make an external one work. I know you mentioned not using your March pulley but even if you wanted to it wouldn't work cause the Denso pulley is bolted on like a GM's Delco alt. The mounting brackets are different also so your March brackets won't work. I thought about doing a denso swap on my Cuda too awhile back but when I ran into these problems I gave up cause I have the March system on mine also. I just changed mine over to the newer dual field system with a 60 amp alt. Works real good now.