In addition to the above mentioned differences, the B-Body LT1s also had a lower lift, shorter duration cam profile.
They also had a slightly more restrictive intake duct system. PCM programming for the automatic shifting was softer, and the OptiSpark caps in all B-Body LT1s were ventilated in all years, not just '95 and later. PCM fuel cutoff for some B-cars was set a 255 MPH (effectively no cutoff) so the cars would be drag-limited for top speed. The RPM limit on the OBD-I programs I've looked at is above 10,000 RPM =- Again, effectively no cutoff. The real "RPM limiter" was the use of the standard 85# valve springs instead of something more suitable for a good roller cam, and other intake and exhaust restrictions. (
Mine turns 6,500 RPM for short bursts regularly - often enough so that I frequently cross the 1,000' traps in second gear at about 92MPH.) I haven't looked that closely at the OBD-II programming for the B-Body LT1s, so that may have changed after 1995.
However, the "heat soak" theory is all but invalid with the reverse flow cooling system, and the better flowing iron heads had greater potential for power in all ranges. The cars needed the extra power potential to help offset the ridiculously low K-Factor (stall RPM) of the stock torque converters, 3.08 axles, and more restrictive exhaust.
I run my '94 BBBarge at 10.8:1 static (52cc chambers) with 2.02/1.60 valves (something that can't easily be done with aluminum heads), .510/.540 lobe lifts, and can get by on 87 octane if necessary. Head "heat soak" is not a problem. It it is, someone forgot to tell that to my car. Yes, it only run mid- to high 13's, but I can keep a Honda Civic in the trunk as a spare.