Posted 2021-April-02, 02:44
Looking at it without the UI:
First of all I am assuming that there is no clear agreement with partner over whether 3♣ is forcing. With a normal overcall hand (i.e. less than 15 hcp), I expect to bid game over opposing 1NT only when our side has a trump fit. So in principle 3♣ is not forcing. The difficulty for me is that I would have doubled 1NT every day of the week.
However, you have taken a minority decision not to double 1NT, and could reasonably hope to have got 300+ by doing so (especially as the opps apparently cannot escape into Clubs). So you need game to beat the 300s. My answer is influenced by the fact that I play in a location where 12-14 is the usual 1NT range, and I play a penalty double. This may be less persuasive if most of the field plays 15-17?
With the UI, it's more difficult. My reasonable choices are 3NT and pass. I think the UI tips me off that 3NT is likely to be better than passing, so I'd pass.