H51 Police Interceptor 440?

My cousin is pretty set on buying a very nice '72 Polara with a 440 in it. The guy selling the car showed us the fender tag and the 'H51' code saying that it meant the engine was an HP 440 c.i. "Police Interceptor" with factory Holley 4-bbl. What exactly did these engines have in them? Since it's a '72 the engine must be low compression, right? The engine is all stock with only 41k miles, and we're planning on just adding dual exhaust, Performer intake, DemonSizzler-tuned Thermo-Quad, and a good aftermarket ignition system to improve gas mileage and performance.

I figured you guys might wanna see this thing, so here goes... BUT DON'T BE GETTING ANY IDEAS lol!!

http://classiccars.com/116916.car