My sister had some guy help her soup up her '68 Mustang. She was drag racing it at U.S. 30 Drag Strip near Chicago. I do not recall if she did any good, ;)
I had a couple of slant sixes, one in a Valiant just like that. Well, looked like it anyway. They are torquey. That one is packing a Roots, I'm sure, among other things. Probably the only thing original is the block, and it's almost certainly sleeved.