I would suggest staying at 1.25 as you are getting into the blues and he did go lower in the cycle. It would be interesting if 1.25 would do the same with 373. If it doesn't, make note of it and the next time you get a 373 number, you can try 1.5 units only if you can monitor. You mentioned 3 units which I don't think that is what you meant.
Also, last night's high numbers is probably because he got too much insulin. We suggest here in the early stages of data collection, to not shoot below 200. What you can do just like you did last night is stall. Some stall 20-30 minutes and depending on the number, some stall one hour. It is at that time you can determine on whether to skip or keep stalling.