I also think pre-flop is a fold because there's no way 54s gets implieds vs shorties that will have 1.5x pot behind if you call.

Initially I love the flop play. Now I'm not certain. I do think both shorties are most likely to fold and you take down the pot - this alone should make it +EV, though the bet size needed to provoke the folds makes it less so. I don't think any hands you beat will call you though. And I don't think any hands that beat you will fold. I agree any smaller bet size is probably still going to see all the money go in if any of the villains want to play. I'm perfectly willing to discount all pocket pairs due to the flop checks, but that's not the same as ruling them out. I'd guesstimate both villains have premium unpaired paint like AK or AQ as their most likely holdings. It could probably realistically be said that we bet the flop to price out draws, where the draws are probably 6 outs to a higher pair in both cases (some of which discount each other).

The question becomes, is there any bet size that is big enough to price out 5-6 out draws (to better pairs) while being small enough that a bet/fold is correct if either of the villains opts to go all-in? Half pot, $21? In the case of the bigger small stack shoving it would require $40 to call a pot of $124 giving 3 to 1 odds.

It's a strange way of looking at it, because most often I see people manipulating bet sizes to make it correct for themselves to call where my suggestion here is to make it correct for Hero to bet/fold if that is possible.

I don't think there's really a compelling argument for a 1/2 pot b/f line on the flop.

Ok, let's discuss bet/call. The basic idea behind bet/call compared to the current play (which is in effect a shove) is if for metagame reasons it is more likely to either get worse hands to call or better hands to fold. The essence of this question is which play looks more bluffy - shove or PSB? I don't think we'll get better hands to fold, so the question really is if worse hands will call. If we don't require the villains to put in all of their chips they MIGHT call an AK type hand. Maybe PSB is the wrong size for this - maybe $29 or $33 is the right size for a value bet that we want to be called.

Especially the read here is important: "Opponents are both loose, terrible and probably blowing off some money for fun". People who are blowing off money for fun are often reluctant to put in their last chips if they could be left with a stack that they could theoretically rebuild from. By shoving we provoke more folds - if we took a smaller bet size we might be getting worse hands to come along.

Anyway, I'm a noobie, and as said - my initial thought was to dislike the pre-flop call and to love the flop shove.