I sincerely doubt the 750 number. That kind of revenue requires enormous infrastructure and I just don't see it. Ray Franz cites a 1978 financial report that pegged the assets of the WTBTS at $332 million, mostly in property. A public corporation that had those kind of assets 30+ years ago and performed about as well as the economy has grown, as measured for example by the rise in the S&P, should be worth about $4 billion today. The $750 million number would represent a gross return of over 200% on equity alone (ROE). But capital employed by the Watchtower is going to be a lot less than what it has tied up in equity. Return on capital employed (RCE) would have to be probably 2000 %/pa and that is just not realistic at all.
By all means, tax the religions, but does the US have the will to do it? I doubt it. It won't happen here in Canada, either. Our current Prime Minister (Stephen Harper) describes his party's values as Canada's values. He controls things with an iron fist, elminating anyone who does not agree with him. His party's values are his values, and he is a fundamentalist Christian. He is about to lower corporate income taxes in Canada and cut spending in most social sectors. He has cut off funding of women's groups and the arts, is building more and bigger prisons and intends to recriminalise cannabis use. If he could get away with it, he'd reverse the decriminalisation of homosexuality brought about by his visionary predecessor Pierre Trudeau more than 40 years ago. He will do all these things but he will not, ever, tax the churches unless he can preferentially tax the ones he doesn't like, and that would be difficult for even him to do without getting turfed out on his righteous ass.