The service-replacement " '92 Caprice " TBI crate engine I put into my '88 K1500 had flat-tops. Computer had zero problem adapting to the 1/4-point increase in compression ratio. Compression ratio should have been higher-still, but excess piston-to-head clearance offset that. Pistons are typically .025--.030 in the hole, plus the thickness of the head gasket which might be .028 but is more-commonly nearly .040. Pistons are dirt-cheap as OEM replacements, but
the compression height has been dicked-with.
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"I" would have the block square-decked if not zero-decked, to get the pistons high enough to create proper "squish" or "quench" with the cylinder head and gasket selected.
The engine going into Mom's Concours (Nova) got the crank offset-ground rather than shaving excess material from the block. The extra stroke will bring the pistons up (and down) an additional .020. Either way--shaved block, additional stroke, or custom pistons with proper compression height, will get you correct squish/quench distance. Remember that most off-the-shelf pistons are "destroked"; an industry term for
deliberately sabotaging the compression height and destroying squish.
Consider better cylinder heads. This is going to be difficult if Summit has discontinued their aluminum TBI heads. Vortec heads suck on the TBI platform due to EGR problems, the hyperexpensive TBI-to-Vortec-head intake manifold, etc.
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Assure that the radiator is in decent condition to support the renewed engine with--hopefully--additional power. Verify that the A/C condenser isn't restricting airflow with bent/corroded fins, sparrows, 'hoppers, etc. Verify water pump, fan clutch, and fan. High-flow thermostat?
New rubber: Radiator and heater hoses, fan belt (and tensioner?). New engine mounts if you can find decent ones--far as I know, there's no such product available for 4WDs.
When it's my engine, I install brass draincocks in the block-drain holes that aren't occupied with knock sensors. I also install a block heater even though I rarely use 'em.
With the engine out, it may be worthwhile to consider replacing A/C evaproator and/or heater core. The job may/may not be easier with the engine out of the way. Probably need a fresh Dorman replacement heater-hose quick coupler on the intake manifold.
All the usual "tune-up" parts--plugs, plug wires (Route them exactly as original, get fresh plug wire looms as needed.) Distributor cap 'n' rotor. Assure that the distributor mainshaft magnet is in good condition (replace mainshaft as needed). Fuel and air filters, complete scan-tool evaluation of all sensors. Probably replace O2 sensor. Verify fuel pressure.
New transmission torque converter seal? New TV cable?
Adjust DRAC to provide proper speedo readings with 4.56 gears and whatever tires you're using.
All the usual warnings about having the brakes/steering/suspension in adequate shape for safety.