the new trail will indeed depend on the HT angle (which will change if the new fork is shorter) and on the wheel radius.

I'm not sure whether you have 37 or 44 mm rake, the spec sheet differs from your post (and by the way 345 mm is impossibly short for a 700c wheel, 365 is standard). Respectively that gives 65 or 59 mm trail.

Assuming the 650c wheel radius is 313 mm, the new fork will be approx. 335 mm a-t-c and your HT angle (and ST angle) will steep up considerably by 5 deg! And then you'd need something like 10 mm of rake to achieve 60 mm trail.

5 deg seems like a big change so perhaps someone else can confirm. But if it is correct I would NOT recommend a shorter fork. Why the change?