Maybe I'm overthinking this, but... Partner has <4♠, since they didn't bid 2♠ Partner probably has a stiff/void in hearts, 2 on a bad day. Partner has more clubs than diamonds probably. Partner didn't double 2♥, they may not even have 3♠... This means at worst, we are facing a 3244 type hand. I'm quite tempted by 4♣, I think game will certainly have play opposite most hands, but I also don't want to get too high... Although if partner has concentration in ♦, I expect them to have opened 1♦, so it looks like we're facing a 3244 without much wastage, a 3145 with a bit of wastage, or 2146 or something. I feel like I'm missing something, but it seems like 4♣ is a winner.