Is it any good

Hughes converters are well built converters and I wouldn't hesitate using one but from my observations they don't seem to stall as high as their rated. I put a 24-25 in a buddy's 440 powered Challenger and it just barely flashes 2500 rpm and his 440 is real torquey. For that reason I'm with Rusty that it most likely won't make much difference, unless someone has installed a RV torque converter in your car, which may be the case by your description. You really need a looser converter anyway with a 340 and big cam.