When I did this it required a new cowl, dummy engine etc, So the new cowl got scuffed good and an added layer of 5.0 oz.cloth then at the attach points a layer of C/F and .3 oz cloth on top, I went with a cast dummy engine and a 1/8 backer board. all up the new cowl weight is 1,1/4 lbs
This helped eliminate all of the lead that was in the chin, my engine is soft mounted so the soft mount plate is 2/8 cold rolled steel then to get the balance right I had to take out a big chunk in the center.
The other advantage with the plate it seams to dampen the viberation a bit
It is now ready to fly just have to get my test pilot and my days off lined up.
Cheers Bob T