As executor you do have decision making power - but not necessarily the final decision.
Giving people shares (or other estate assets) to satisfy their inheritance entitlements, in full or in part, is permissible and commonplace.
It is called an appropriation - and there are various rules to be met.
Notices must be served and objections can be made. Section 55 of the Succession Act gives further guidance.
CGT consequences can vary too.
If you are making appropriations, the date of death is not the correct valuation date. It should be at, or as close as practicable to, the date of actual distribution. There is a large body of case law on this.
Are you handling the administration yourself? If so, the best advice is to circulate to all beneficiaries a full copy of the proposed distribution scheme and make sure that they are all in agreement. In other words, rather than quoting the law chapter and verse, more a sort of "here is what I am going to do as soon as everybody signs off on it"
But, echoing Ravima, you might be as well off to sell the lot and tell them to just buy shares with their money, if that is what they want.