How much horsepower

Honestly, your question is gonna have an open ended answer. I've seen stock engines break tires. It's depends on road temp, the surface material type, street or track, is the track prepped. Obviously going with the striker is gonna exaggerate the traction issues but you can always throw a set of pure slicks on it if you do hit the track and help that. A suregip honestly is gonna be needed regardless. That said, unless you're gonna drag race it every weekend, I wouldn't stroke it.
The was leaning that way. The old 273 was tired and the rebuilt 340 will be a vast improvement. Thanks for being the voice of reson.