I'm not an attorney, but I have done a quite a few acquisitions for megacorp, so I have seen it from the other side, and have had to try to create win-win situations for us and the seller. Tax always makes it tricky.
Been a while, but IIRC:
If you are selling your company (i.e., selling the shares of a legal entity), it would be cap gains, taxed at the lower rate. If you are not incorporated, operate as a sole proprietorship, you would be selling the business, not the company, and thus I believe the proceeds would be considered current income, and subject to income tax (not cap gains tax).
If you operate as a corporation, but sell the business and not the corp, the corporation will be subject to current income tax. If you as the shareholder then wind-up the company or liquidate the shares of that corporation, you then pay capital gains tax on the distribution of the proceeds. That means you are taxed twice: once at current income rates in the corporation, and 2) a second time personally at cap gains rates when you distribute the proceeds.
You need to have a good lawyer and accountant, working together, to help you structure the deal so that your good uncle doesn't get the better part of your years of hard work.
As I said, I am not an attorney, and this should not be construed as legal advice, but rather, as advice to get some really good legal advice.