Can I find out how much the cash portion of a cash & miles purchase will be without having the points in my flying blue account?

I'm looking a reward ticket on KLM that costs 165,500 points. I currently have about 134,000 chase ultimate rewards points. My understanding is that I could transfer those chase points to flying blue and then purchase the ticket using the cash & miles option (pay 75% with points, 25% with cash). My question is: how is the cost of the 25% in cash calculated? Is it 25% of the cash price of the ticket? Or is it the cash value of 25% of the points price? I don't want to transfer all my chase points over only to see that the 25% I need to pay is much higher than expected, but it doesn't seem to possible to see how much it will cost without having the points in my flying blue account. Is this correct? Thanks in advance!