I'd post on the forums at this site (free to join):
People post there frequently in regards to specific model numbers. And most posts seem to get a response from my experience.
Or call Cliff's High Performance directly - last time I did I ended up talking to the owner (Cliff) and he was very helpful.
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1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.