I was able to change all 8 plugs on my 440 from above. But it requires a LOT of patience! And as a side note, the diff between your carb and the 4737S is 100 cfm (750).
Longtime Mopar owner, with this being my 4th Cuda. It's a 'U' code, one of 334 made in 1970. Looking forward to finding out and sharing info, and just chewing the fat!