Not sure on the specifics of the 272, 15-16 isn't horrible, just not right for a stock engine. What's not stock? Was a bigger cam used? How big is the 'wiggle'? Google 'vacuum gauge test' - there are some very good reads on the subject. Here is a list of readings:
* a lower reading indicates possible incorrect timing, incorrect valve timing or adjustment, incorrect setting of idle mixture, worn piston rings, or leak in intake manifold.
* readings that change slowly indicate incorrect setting of idle mixture screw.
* readings that change quickly indicate sticky valve guides, burned valve sets, or leak in head gasket.
testing at 2000 rpm
* a lower reading indicates possible restriction in exhaust.
* oscillating reading indicates possible weak valve springs.
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* gauge reading steady 17-22 in Hg indicates normal
engine in good condition.
* gauge reading low (15-20 in Hg) but steady indicates late ignition or valve timing, low compression, stuck throttle valve, leaking carburetor or manifold gasket.
* gauge reading steady but dropping regularly indicates burnt valve or improper valve clearance.
* gauge reading dropping gradually at idle indicates choked muffler or obstruction in exhaust.
* gauge reading slowly dropping to zero as
engine speeds up indicates choked muffler.
* gauge reading fluctuating between 15 and 20 in Hg at idle indicates stuck valve or ignition miss.
* gauge reading drifting indicates improper carburetor adjustment or minor intake leak at carburetor or manifold.
* gauge reading fluctuating as
engine speed increases indicates weak valve springs, worn valve stem guides.
* gauge reading vibrating excessively at idle but steady as
engine speeds up indicates worn valve guides.
* gauge reading vibrating excessively at all speeds indicates leaky cylinder head gasket.
