If your business was a sole proprietorship reporting on Schedule C, your net earnings for the purpose of calculating your maximum SEP contribution would be your net profit minus the deductible portion of self-employment taxes. Excluded foreign-earned income would count toward net earnings for making a SEP contribution. Excluded foreign-earned income only would not count toward compensation for making a regular personal traditional or Roth IRA contribution.
However, you have an incorporated business. Assuming it's a US corporation filing Form 1120 or 1120S, your maximum SEP contribution is based on the amount of compensation reported on your W-2 and the deduction is taken on the corporate tax return regardless of whether or not you exclude the foreign-earned income on your personal tax return. If the business is not a US corporation, it can't have a SEP plan. Your maximum regular personal IRA contribution would be limited by the amount in box 1 of your W-2 minus any excluded foreign-earned income.
To avoid your IRA custodian making mistakes in reporting contributions as either SEP or regular traditional IRA contributions, SEP and regular personal traditional IRA contributions should be made to different IRAs. Some custodians do not permit regular personal contributions to be made to an IRA that is designated as a SEP IRA.
