What year truck?? I built a 440 Shortram motor,(same length as the long ram) and put it in my '81 W-150. You'll need to use a set of 60'e vintage valve covers, even the early 70's are to high and the rams won't clear. Also, you will probably have to ditch the brake booster and move the master cylinder. I moved mine 3" to the center and tied down the driver's side motor mount as it has 1/4" clearance.
After telling you all the bad parts now the good. They make mind-blowing low-end torque. My motor is 9.2-1 with E-STREET heads and an MP.528 solid cam with Doug's 1-3/4" headers. It make 512ftlbs@2500 and 543ftlbs@3800.
When choosing a cam for your motor err on the conservative side. The rams won't work with a big cam. The .528 was about as big as I dared go with shortrams. The carb pad will accept 500 CFM Edelbrocks , possibly 600's too but don't try and over carb the rams, Dave