Here's a low cr 360 at one point around 3:45 time mark, stock low cr, 1.88 valves, 2bbl cammed with factory 360 4bbl intake and exhaust manifolds and a Qjet makes 264 hp. That's basically the 340's 275 hp power number but without cam cr and 2.02. I know the 360 got 20 cid on a 340 :)
When he added a similar cam as a 340 xe250h and 2.02 heads with a bit of work so maybe on par with x heads but with headers and aftermarket intake but still low cr made 339 hp.
What did a 340 make? Who knows but we do know they were fast.