To help mitigate the rattle when using a 13# (Fidanza), the following steps together resulted in almost completely eliminating (you be the judge) while retaining the stock PP:
Camaro, sprung hub disc (Summit) part #381039
Increasing the idle speed to 850-900 rpm
Accel injectors #150821
Also, unrelated to the noise issue, an ARP bolt kit and tap was purchased. The purpose was to facilitated drilling and tapping the holes in the FW to approx 1+" to give the bolts a little more purchase due the aluminum vs. cast iron to secure the PP to the FW. I also used new Grade 8 bolts and red Lock-Tite to secure the FW to the crank. All GOOD for 6 seasons now w/o issues.
See what you think:
https://www.youtube.com/watch?v=y1YFa8ruh8A
Note: At the time this video was shot, it was 21ºF and the transmission was cold, and filled with synthetic Castrol TWS which is no longer available. It now has Redline Shock=Proof (HD) synthetic, which seems to work about the same as the TWS, far as I can tell.