I have the same question. I used the 34-6 Holley metering blocks on our last set of 660's (late 80's) and they worked great. Now days there are billet blocks offered all over the place. Which ones to use, or just stick to the Holley conversion blocks.?? I have tried to find out which Holley baseplates to use for a while as well. There are also lots of different billet base plates out there now. I have been told by people that have had the baseplate conversion done that it really made a big difference
. I could send them out and have someone else put them on, but I'm quite capable of machining the carb bodies, and I think it would be a fun project to dive into. If you find any info on any of this, and it's not on this thread, please send me a PM with anything you can share.
Thank You Tom