OK - Reconstruction.
(I am not even going to countenance title-play-offs. That is Mickey Mouse thinking for Mickey Mouse sports).
You first deal breaker (or strictly speaking, deal-maker) with Mr. Murdoch is 4 Old Firm matches per season. So forget about 16 or 18 team leagues.
10 is one number which guarantees the requisite number of OF duels - Good Luck getting the majority of current 12 Premiership clubs to agree to reduce their numbers, though.
You could just about squeeze 12 clubs playing each other 4 times into a season (we have done it before), but it leaves precious little room for wriggle in the event of a bad winter or (less likely, I know) someone having a run in Europe.
14 would work, with a 6/8 or 8/6 (or even 7/7) split, after each side plays each other twice. But that means a split around late January or early February. A long time afterwards for the majority of clubs to spend treading water.
So how about we try a top league of 12, which splits into 6/6 after clubs play each other three times? That would be worth a go.
Oh, wait a minute...............