according to several articles on the net, the 9c1 cars get the aluminum heads, along with reverse cooling that cools the heads first then the block.
In 1994 the Caprice received the new-generation GM engines, including an optional detuned version of the Corvette's LT1 350 cu in (5.7 L) engine that put out 260 hp (194 kW) and 330 ft·lbf (447 N·m) of torque. The standard engine in all sedans even the 9C1 police cars, was the 200hp, L99 265 (4.3 L) V8. The LT1 was optional in the 9C1 police-package and standard in the wagon. The LT1 350 was standard in the civilian sedans, with the addition of the B4U towing package. The towing package also gave a heavy duty suspension nearly identical to the 9C1 police car suspension. 2.93 gears, heavy duty cooling, heavy duty rear drum brakes and positraction were standard with the towing package. The 265 (4.3 L) L99, and 350 (5.7 L) LT1 look nearly identical externally. Many 4.3 L99 equipped sedans are passed off as 5.7 LT1 cars. The 8th digit in the VIN number is the Engine code. W: 4.3 L L99, P: 5.7 L LT1. The 1994 Caprice's interior had a redesign which featured a Camaro steering wheel, digital speedometer and a new console. In 1994 Chevrolet also revived the Impala SS name by upgrading the 9C1 (police package) with a special body-colored grille, spoiler, C-pillar trim, special interior treatment and 17" alloy rims made by ROH on BF Goodrich 255/50/17 tires. In 1995 the sedan's rear quarter windows were redesigned to match the style of the Impala SS, and new wing mirrors were fitted. In 1996, the Impala SS was improved by moving the shifter to the floor console and adding analog gauges as opposed to digital gauges in the standard Caprice.
The Caprice 9C1 with the LT1 engine became one of the fastest and most popular modern day police vehicles. This vehicle established such strong devotion by many police departments that a cottage industry thrived in refurbishing Caprices for continued police service after GM discontinued production of the car.
theres a lot of info out there and some of it doesn't agree with others, i guess i'll have to wait till the car gets here to sort it all out...