Raising CYA with Dichlor - need formula please

I'm sure the answer is here but I've found some conflicting numbers so sorry for the repeat post (most likely):
I've refilled the pool after a new paint job (whole saga there on what why but I'll try to stay positive) and working on getting my levels tuned in. Also new this year is a AutoPilot Salt system.
So I know I need to maintain FC and raise CYA to the 70-80 range to get stabilized and then bring the salt system online. My question is how much Dichlor to add to hit about 70ppm on the CYA? I believe the root question here is how many ppm of CYA is introduced per X ppm of FC. I can get X but what's the ratio on the CYA side?

Thanks all.

Dichlor should add about 9ppm CYA for every 10ppm FC. 10lbs of dichlor should add about 15ppm CYA to a 40,000 gallon pool.

Awesome, thanks BigDave for the info.
Leads to a couple other questions:
1. If I want to get to ~70 CYA (using 70 as my goal with my new SWG - unless someone says I'm off there) I'll need ~50 lbs. of dichlor, sound right?
2. My plan was to use up what I had left from last year's dichlor to get it stabilized but if I'm right above I'll need to buy more. I'm OK doing that or can I buy straight up Cyanuric Acid and use that instead of dichlor for the stabilizer and go ahead and get the salt system running for the chlorine maintenance?

You can certainly use Dichlor in your pool to simultaneously add chlorine and raise the CYA level though obviously you can't raise the CYA that quickly since you don't want your FC to get too high. Nevertheless, to use up what you've got by adding it over time is fine. Then if you still need more CYA you can just buy pure CYA from your pool store, as you wrote.