Can you show your assumptions on the 5 grove analysis?

As I understand Buffet's suggested method in the 2018 annual letter, it is to first add the four asset laden groves:

Grove 1 - BRK subsidiaries
Grove 2 - Equities
Grove 3 - Shared control companies
Grove 4 - Cash, cash equivalents, etc.

Then subtract an appropriate amount for taxes eventually payable on the sale of marketable securities.

This two-step method is summarized at page 2018 of the letter:

"I believe Berkshire's intrinsic value can be _approximated_ by summing the values of our four asset-laden
groves and then subtracting an appropriate amount for taxes eventually payable on the sale of marketable securities."

Grove 5 is "Insurance". Grove 5 provides cost free finance of the four groves, but it is also ideally better than cost free. I take Buffett to mean, given the above quoted text, that the approximate of BRK's intrinsic value assumes this figure to be $0, with its benefit as zero cost financing showing up in the first four groves. That said, he then goes on to suggest BRK is worth considerably more than the sum of its parts, etc., thereby suggesting that the above method is a conservative estimate (or that's how I read it).

What are your numbers and assumptions to get to $323? I'm curious as its more bearish than my own outlook. I'd provide my own specific 5 grove analysis but I haven't done it in a spell. Might be time to do so.