6X-8 heads maybe 8:1, 6X-4 will be 8.5:1 at best.
Choose your cam accordingly.
I’d be looking for 1970 #13 400 heads, usually around 77 to 80cc chambers although advertised as 72cc. This will bump you up around 9.5:1.
Bonus - #13 heads won’t need any finagling to match up the center exhaust crossover to your Tri-Power, unlike any 1972 and later heads like 4X or 6X.
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1964 Tempest Coupe LS3/4L70E/3.42
1964 Le Mans Convertible 421 HO/TH350/3.08
2002 WS6 Convertible LS1/4L60E/3.23
1966 VW Type 2 Single Cab Pickup 140hp 2276
1956 VW Type 2 Panel Van 36hp 1200
1957 VW Type 1 Beetle 180hp 2276
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