In my experiences putting FI on an older vehicle is not all that cost prohibitive you just have to be very attention to detail oriented, Being a younger man you will probably pick up the ins and outs of FI quicker than most of us older carburetor guys. With that being said 70s, 80s, and 90,s rams are all nice looking and lend themselves well to hot-rodding so I don't think you can go wrong with any of those decades of Rams. I would say the deciding factor for me would be availability of trucks and parts, newer years being more readily available. good luck to ya.