I would work the price down. When the engine is warmed up, pop the hood, and pull the breather from the valve cover, see how much blow-by smoke is coming out. Don't get hung up on the HP stamp. All 440s are great motors. The 915 heads may have the smaller 1.60" exhaust valves. 1.74" are the more desirable exhaust valves. Has there been any head work? 3 angle grind, 1.74" valves installed? Double roller timing chain? Some of the later engines had nylon cam gears, yours should not. Does this also have the MSD 6A unit or just the distributor? How is the idle? smooth or a tone of a larger cam? What is the oil pressure at warmed up? There is no need to over-cam these motors. The 440 is a very torquey engine. In my 440 powered Ramcharger, I could smash the brake down, press the gas, and the vehicle would move forward DRAGGING THE FRONT TIRES. This was a 3.21 geared 4x4 running 31" BFG tires. Enjoy the motor. My build was: 440+.030 346 heads Edelbrock intake, Hooker headers, dual exhaust, double roller timing chain Hughes camshaft HE1423BL 214/223Deg. @.050 .470I .504E 112° Hughes has revised their cams, this one is no longer available.
Bronze valve guides. This cam gave great vacuum for the power brakes. Engine would suck down to 25" of Hg vacuum when letting off from a freeway speed, RPM was ~2400.
Good luck, enjoy.