72 demon 340 needs a new carb! strong opinion or suggestion?

Thanks, Dan. Yeah it looks like Demon Sizzler quit doing them. But I think the correct thermoquad for the 72 demon (TQ 6139S) is more like 650 cfm, from the google-ing I did. I'm not sure what affect it would have to swap for a 850, but I'd rather not adversely affect the gas mileage since I've been happy with the performance with the stock carb anyway. thoughts? am i wrong?

and does anyone have an opinion re: aftermarket replacements if I can't find a rebuilt thermoquad that's the correct one for this car?

thanks!!