Serendipity - A genuine Allard J2X has just appeared for sale on Car&Classic.

https://www.carandclassic.co.uk/car/C1378149

When the cars were built new Allard weren't allowed to import American engines, due to post-war restrictions, so all UK cars had the side valve Ford (or Mercury) V8 fitted. Cars exported to the USA usually went engineless and were fitted with a big V8 on arrival. Cadillac being the preferred choice.

Naturally many UK cars have since been upgraded as has this Singapore export model.