If you're N/A making 345 bhp, 24s should be running at ~90% duty cycle (assuming a very conservative .5 BSFC). So, as mentioned, you're fine. If you REALLY want to confirm it to yourself, you don't need a wideband. You can use a digital multimeter off of an injector and have a buddy read it while you're at WOT.
If you pay attention to the way Ford selects injectors, you'll find that in most applications, they put 1 lbs of injector for every 10hp they rated their cars. So, 30 lbs are probably "better", in that they'll keep the duty cycle down, but injectors either support the power or they don't. Yours do, or at least should, and therefore you'll end up wasting your money for nothing with this upgrade, now. If you go forced induction later, or install a tuner of some kind, 30s may be the wrong pick at that point. So, save the money, and get the right ones when you need em.
Before you go down some expensive rabbit hole, would you mind explaining why you think you need to swap them out? It seems like you read 30s are preferred and that's got you wanting to throw away money.
