Second job / part-time / split-working salary advice

I work full time, 40 hours a week Monday-Friday, and earn £46,350 for Company A

My salary is going up in April 3 by 3.5% due to a companywide increase to £47,972.25

My boss who owns Company A also wants me to work for Company B. I want to do this. Company B offers me a massive opportunity.

They want me to split my time 60/40, 3 days a week with Company A and 2 days a week with Company B.

Now, on my current salary (pre-increase), I earn £178.27 a day.

On my new salary, post a 3.5% uplift, that goes to the £47,927.25 annually.

Over 3 days a week, that goes down to £28,783.30 ?

So, I am down £19,143.90 if I go 3 days a week with Company A?

Company B has asked me to name my price for working 2 days a week.

I want to make sure I am at least earning the same, obviously! But it’s a chance to make more money, which my boss at Company A is supportive of.

I want my annual earnings to be around £60,000 a year at least. Company B has plenty of cash.

Please, can someone help me with what my day rate should be on the following scenarios and how many I should be asking for from Company B?

1 - How much would I need to say my day rate and annual salary should be with Company B to break even?

2 - I want my total annual earnings across Company A & Company B to be at least £60,000 a year, possibly more. I believe that this would mean Company B would need to pay me at least £31,216.65 for two days’ work a week?

Is that correct, and what is the day rate on that, please?

3 – Speaking with payroll at Company A, they have said that taking a second job will impact my tax and that if I go over £50,000 a year, I’ll be paying 40% through an adjustment.

I spoke with HMRC and they told me not to split my tax allowance.

4- At the moment, Company A pays me a decent pension; it’s about 10-11% of my annual gross earnings. It will not be as high at Company B. I think it will be 3% minimum.

Therefore, how much should I be asking for in my new salary from Company B per day and annually?

Thank you all very much for your help.