225 slant 6 or 360 v8

It has a bunch of head work done to it. Oversized valves 3 angle valve job and a port job. the builder said it beat stock 4.7l mustang gts (275hp) in the 1/8th mile with 3.73s. i beleive he said it ran in the 8s? but it is very built for a slant and he said he never dynoed it but it beats stock mustangs all day.