I'm going to say around 400hp. My 340 with Curtis Boggs ported Edelbrocks, a larger hydraulic cam, 11.4-1 compression, Weiand X-Cellerator intake, 727, 4.30 gears and a 275 radial ran 7.24 @ 92mph in the 1/8th. It was 3240# at the time, IIRC the Wallace calculator put it in the 450 range.
Andre at Edge Racing converters did the converter. The 340 went 1.52-53 60', I sent it back after building my 408 and had it reconfigured and it went 1.38 at the same weight until the 408 killed it. My $1250 Ultimate Converter Concepts converter has never been in the 1.30s or low .40s for that matter.
BTW both converters were built without any dyno numbers.