Lee.....I THINK Mark is asking if there is a modern production meter which approximates the dimensions of the VU meters used in the PL 400 Series I faceplate. If he is ordering new production faceplates, it might be very cool to have a meter which is really good to replace the meters which were not very good even by 1970 standards. I may have misinterpreted Mark's post, but that is what I came up with. If there is a modern production meter that is close to the size of the PL meters, now would be the best time to incorperate the change in dimensions....
The circuit changes are a different story, and it'll take someone else to address that..
An entirely NEW FACEPLATE WITH entirely NEW FAST ACCURATE METERS !!!
I hope that is clear as mud...