"they have not received the contract sale price to date but will happen sometime this year " 

So was there a purchase agreement signed in 2022 with interest only for the first year and interest and principal in 2023 ?      If yes, then the 6252 would be calculated showing a gross profit.  You then enter $0 principal received and $xxx interest for 2022.   Client is only taxed on the interest for 2022 and none of the gross profit.