Matt Steen's valiant with a 273 runs in the 11's but it is a purpose built race car. SS/KA index is 11.25. There;s a lot of 340 cars that don't run low 11's. Can you make 350-400 horse with a 273? You might be able to but why? View attachment 1716334470
NHRA super stock is a whole different world. He probably has huge money in the engine. Like 20-$30,000! And a $5000 transmission with light weight parts and bearings throughout. And the rest of the car is well sorted out to run those amazing times.
Not much similar to a bracket car or weekend hotrod.