Doug, Some help to your questions may be the following: The 340hp had a stroke of 3.375 (9.5-1 comp) and the 360 hp had a stroke of 3.750 (10-1 comp). Also, the 340hp had 1.60 in head dia valves and the 360hp had 1.75 in dia. You could installed the longer connecting rods, but there would be more backpressure in you exhaust. You would probably need to replace the heads, which will fit, from a 360hp engine. Crash 1964 300-K (360hp) convert [Non-text portions of this message have been removed]