GovCon EarnOut structures for large pending contracts?

Curious if anyone has experience with government contracting M&A and specifically terms for securing a large multi-year contract.

The opportunity I am looking at feels confident they will secure 2 very large contracts that would guarantee revenue over the next 5 years. The seller wants this to be captured in the purchase price. I am assuming some sort of forgivable note tied to performance (perhaps revenue?) here would support this.

Thoughts?