Which is it, a SEP-IRA or a self-employed 401(k). It can't be both.
For 2022, the maximum SEP contribution would be $61,000 assuming you have $305,000 of net earnings from self-employment. Net earnings from self-employment are net profit minus the deductible portion of self-employment taxes.
To be able to contribute $67,500, the plan would have to be a self-employed 401(k) and your net profit would likely have to be at least about $215,000 of net profit.