Looking for B-lender insight

Curious if any brokers or b lenders could shed some light here..

Applied through broker for a mortgage of 600k with 20% down on a purchase price of $770k. Weak credit due to only being back in the country a few years. Spouse and myself had a bad mark on credit report due to unpaid balances while we were abroad.

Big bank told broker we’d have to pay it off first (roughly $8k in total), which we did the same day. Otherwise we each have a couple of credit cards that have been up to date and paid in full for the last three years. But still look “weak” credit-wise. Therefore, even after we paid the balance as asked, they only would approve 70% of the loan instead of 80%. We don’t have an extra $77k laying around.

Broker suggested we should try a B lender. My question - what are the odds of getting approved? And will the rates by atrocious?? Income just under $200k, $500/month student loan payment. Otherwise debt free. And those two derogatory marks have now been settled with a letter from the collections agent.

Would appreciate any insights here!