Use primary records: insurer proposals and binders, certificates of coverage, premium invoices and payment confirmations, licence and permit applications with fee receipts, inspection correspondence, and vendor quotes for items not yet purchased. A spreadsheet line is a summary, not evidence, so pair each figure with the document behind it.
Label each figure as paid, committed or quoted
Build the file so a reader can tell at a glance which amounts have left the account, which are contractually owed, and which are still estimates. Where funds came from a lender, keep the loan agreement and the collateral description with the payment records, because what secures the loan affects how the money is viewed. Gaps found later can usually be supplemented, so flag them now instead of hiding them behind a rounded total.
Ask the seller for three years of financial statements, the employee list with wage records, the equipment titles, the permits that must transfer and the lease assignment terms, because those documents feed the substantiality and marginality evidence. A signed commercial lease with payments made, purchase invoices for trucks, trailers and equipment matched to bank debits, deposits with suppliers, business insurance in force, payroll registrations and initial wages paid all qualify.