Answer

How much is the gain on sale of the business venture?

Being a US resident- you are subject to tax on world wide income though you can get a credit for tax you paid to the foreign country to some extent and hence avoid double taxation.

You cannot avoid tax by not bringing the funds in US or leaving it in a interest bearing account outside US. These will be subject to reporting in any case.

Let me know if you have any question.

Please note: This advice is provided with the understanding that all the relevant facts have been provided by you. Any change in facts might affect the advice given and hence may not be relied on in such cases. Nothing contained in this reply was intended or written to be used, can be used by any taxpayer, or may be relied upon or used by any taxpayer for the purposes of avoiding penalties that may be imposed on the taxpayer under the Internal Revenue Code of 1986, as amended.