Search Fund and IS Legal Engagement Structures

I'm looking at deals at a variety of sizes given my geographic focus and, as such, am open to both a self-funded search fund and independent sponsor model. Curious on what legal engagement letter terms typically look like (or should look like) for these models. Obviously there may be hourly rates, but do people have examples of how failed deal fees are charged, etc? I know McGuire Woods is a thought leader in the IS space, so curious if others have worked with them and understand how they communicate cost upfront (along with leaders in the Self-Funded space). This would all help me educate the advisors I've worked with in the past on more traditional M&A deals (strategic/PE).