Re: 396 horsepower rating?
THE ONLY DIFFERENCE BETWEEN THE 396 325 & 350 HP MOTORS in 68 WAS THE CAM.
GM put what they called was the high lift high perf hyd flat tappet cam in the 350hp motor.
The stock GM L35 396/325hp cam had approx 198/200 deg dur @.05,.398/.398 lift,114 Deg L/S angle.
The stock L34 396/350hp cam had 214/218 deg dur @.05,.461/.480 lift,115 deg L/S angle which was still a very mild cam for a BBC and had last 3 digets of 986 in the pt#. I sold an NOS GM L34 396/350hp 986 cam on ebay in the original contaner for $250.
You can look to see what the code is stamped on the pad in front of the pass side head that will tell if its a 325 or 350hp motor if the block has never been decked durring a rbld.
The casting # on the rear of the block is the same for both motors so you cant go by that.
There are blue print copies of these cams by comp & crane but its crazy to use that 40yr old tech . There are much better profiles out there today that will far out power thoses old cam designs and still idle well and have good dirieability to boot.
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)