I did install one of these STIC metering blocks in my big bore 327 and it is honestly the best change I have made to my GG in a very long time and IMO well worth the money. This is the post with more details on Thumpertalk.
https://thumpertalk.com/forums/topic...ad-stic-xc300/
I purchased my STIC metering block from HPR
http://www.hpracedevelopment.com/ I assume the two companies are related as the dyno sheet for on the STIC SuperTorque site says HP Racie Develoment.