Okay, let me give you this from the UK law point of view and from a practical point of view. It may or may not answer your questions but at least then you are no worse off than you were.
In the UK, all the enforceability issues would be dealt with in the business sale agreement.
The promissory note and personal guarantee is all well and good and, provided they are properly drafted and executed, perfectly enforceable.
However, issues arise if the buyer simply does not pay all of the money or some of the money.
If you are in the UK, then there are practical difficulties in trying to enforce a UK agreement in respect of assets in Israel.
If the assets were in the UK, not only could you have a personal charge, you could have a charge over the assets and if this was land or property, you could have a charge over that which means that it could not be sold until you were paid off.
As the companies in the UK, what you could have is a charge over the company and the company assets.
You can word the agreement (this is where you really need a lawyer) such that you retain a huge interest in the company until such time as all the money has been paid in full and the timescale for paying in full even in default, is specified. In default, you could have it so that the company reverts to you and you keep the rest of the money dealing with it as deposit. You have to be very careful with the criteria and the wording but that is the general gist of it.
Because of the amount of money involved here and the potential for you losing $400,000, I would strongly suggest that any business agreement is properly drafted by solicitors either in the UK or Israel although, to be honest, the English judicial system has been the model for the rest of the world and you might want to therefore rely on English law. Certainly, I would as do many countries throughout the world.
A judgement made in the English court is perfectly enforceable in Israel as you would read here.
you can download an interesting article on personal guarantees in Israel from this page.