I wouldn't recommend paying a minister a percentage of the church's income...HOWEVER I do understand that a percentage pay sometimes is the only way some smaller churches can pay their ministers due to the unpredictability of the church's income.
BUT there are a some very important steps you should take before agreeing to pay your minister a percentage. See this page for those steps ... including a CAP: https://www.freechurchaccounting.com/minister.html
or just click the bottom link "Simply click here to return to Minister Employee."
And if you really want to go down a rabbit hole...see this VERY long and passionate post on "What Percentage of Budget is Average for Salaries: https://www.freechurchaccounting.com/what-percentage-of-budget-is-average-for-salaries.html