440 camshaft id

Could always mock it up in a block (or on V-blocks on the bench) and use a dial indicator... I see what looks like fine rust pitting - what kind of shape are the lobes in? It needs to be checked for lobe taper also if you're going to reuse it.
Frankly, as inexpensive as hydraulic flat-tappet cams are, especially for your hp goal, I would seriously consider just buying a new cam/lifter set.