I've been trying to find info on the 1956 265 cu. in. 240 hp. engine and have found an awful lot of conflicting info both in on line searches and from small block lovers on here. So far what I've come up with is that the 240 hp. was a Corvette only option even though there is some mention of this engine being in some passenger cars. I've had small blocks a long time ago '66 Nova, '65 'vette, '68 vette. etc but that was a long time ago so I'm really out of touch with these things, I've been looking at a 265 that the owner has been told by a small block "expert" that it is a 240 hp. I'm finding conflicting info on line as to this claim and would really like to get it cleared up. The engine in question has a suffix on the ID. # of GS which from what I can find is a 225 hp. stick shift dual exhaust passenger car. The intake is 3731394, heads, 3734077, Carbs 2419s, and 2362s heads have the two tower casting. Was the only difference between 225 hp. and 240 hp. the high lift cam? I saw in one search that the 240 hp. was over rated and didn't produce that much hp. So was it just a 225 hp. with a different cam promoted as a racing engine? Any help would be much appreciated and thanks to all who have tried to help out so far, just an awful lot of conflicting info out there on these engines.