I ran a "service replacement" GM "new" crate engine "12513151 - 5.7l (L05)1991-1993 Chevy Caprice (Exc. 9C1 Police Package), 1991-1993 Buick Roadmaster, 1991-1993 Cadillac Fleetwood Brougham"
in my '88 K1500 standard-cab, long bed for something like 18 years. Yeah, that's probably less of a load than a bigass van.
It failed due to a popped head gasket between #3 and #5, which then blowtorched the block and head.
I had Edelbrock "TES" Tubular Exhaust System "shorty headers", a monolithic "high flow" catalyst, and--while it lasted--a Flowmaster cat-back exhaust. All accessories except the fragile GM heater quick-connect and the exhaust system were transferred from the original engine including the knock sensor and--for about two weeks--the oil pressure sending unit. Ended up with "low oil pressure" which turned out to be the first of several oil sending unit failures. After a couple years, I also had issues with a faulty O2 sensor that defied me for the longest time--it tested just fine at lower engine speed, but went false-lean at highway speed causing the fuel trims to go way rich and lit-up the MIL. This also caused me to replace the TBI unit (with injectors) with a similar-but-newer TBI unit from the Treasure Yard, but there was nothing wrong with the original TBI/injectors.
Ran flawlessly on the OEM computer tune once the O2 sensor was replaced. Zero issues with knock/detonation on my usual 87 octane/10% Ethanol swill. Not much more power than the 230K-mile engine it replaced, which I found disappointing. I have no doubt that a proper aftermarket tune would have perked it up, but that's beyond me even now.
For the record, I currently have a Vortec short-block with aftermarket aluminum heads and intake manifold, that same Treasure Yard TBI unit, and essentially all the same accessories, still running on the same OEM computer tune but with mildly-jacked-up ignition advance and fuel pressure. Still with disappointing power although better than stock or the Caprice engine, and a little bit of hesitation only during warm-up, only in cold weather.