I'm running into the same problem. I have the Fluidamper on my B-Block and I want to mount the 36-1 trigger wheel I got from AndyF. But I need a spacer since the pulley mounting area on the Fluidamper is recessed (actually, the damper ring is thicker). I haven't measured how thick of a spacer I need yet but I see the spacer that Mancini sells (http://www.manciniracing.com/bicrpusp.html) is 0.375" (3/8") thick for $47. And Mancini has another spacer (http://www.manciniracing.com/prprpusp.html) that's 0.512" thick and costs $23. The Doty spacer (https://www.dotymi.com/motor-sports/21-mopar-crankshaft-pulley-spacer-.html) is 0.625" thick and costs $41.30.

My plan is to measure how much I need to space out to get a little proud of the Fluidamper ring since I want a clean signal from the trigger wheel. Then I'll buy whichever spacer fits the best. I'll have to check to see if the Fluidamper ring is steel or aluminum. The Doty spacer is the nicest and the thickest. If that was too thick, I could cut it down on my trusty SB Lathe. I see that Jerry mentioned that he could CNC one up for you. I wouldn't hesitate to get a price from him and go that route to get exactly what I needed. I suppose that you might have to fiddle with the pulley mounting bolt holes depending on if you have that one offset bolt hole or not. But I think that the Fluidamper has all the holes evenly spaced.

Of course, once I do all that, I'll have to see where I'm at for the crank pulley alignment with all the other pulleys. At a min, I'll need a shorter crank pulley since I don't want to space all the rest of the pulleys out by whatever I'm adding here. Doty sells v-belt and serpentine pulleys and all the rest of my pulleys are from March so I'll have to do some more pulley alignment engineering.