1960 Other Chevrolet Models

This is hard to say as you can guess but there is alot more that needs to be considered. Like bore and stroke and port matched heads or not and polished exhaust ports or not and runner sizes what spark plugs. Then how much horse power do you get to keep at the rear wheels as this is determined buy the transmission final drive and rear gears and tire size (height of tire meaning diameter). So with a guess about 350 or so. I would call around and find a truck shop as most have dino's and have it dino tested this will give you RWHP which will be less then engine HP. I know this don't really answer you question but I hope it helps in some way. Thanks and have a great day. Buy the way Nice Ride I am a Ford man (Mustangs) but I must say nice ride, you don't see to many 41's.

With so many factors. The best way to have correct horsepower is putting it on a dyno. It will tell you horsepower, power curve, what rpm gives you the most power and top end.

As I said put it on a Dino.