Chris, as far as I know the pre-war engines were 21-stud, not 24. The Ford V8 Flathead was fitted to a huge number (100,000's) of vehicles manufactured by Ford Canada during WW2, ranging from cars & trucks to tracked carriers. Ford in the UK manufactured huge numbers of V8 powered vehicles as well.
Seeing that your friend does not know these details, I guess he's looking for an engine for a hot rod? After WW2, the French fitted the 24-stud V8 engine in the SUMB truck, many of which are now sold on the collector's market. They have various refinements over the WW2 engines and are the one to choose if originality is of no importance. As noted above, RR Services sells parts for these French trucks, incl. engines. As a matter of fact, there's a take-out engine advertised for UKP 1000 on MilWeb as we speak.
Hope this helps,
Hanno