I can tell you that from several experiences in the past,
"taking the crate engine apart and verify and record all the important measurements/dimensions."
at least in my experience is a mixed bag,
obviously you find theres frequently a huge difference in the value of the engine you buy as a crate engine!
you either tend to get depressed at the sloppy slip shod way clearances were maintained during the assembly process,that you obviously paid too much for,
and you look at the parts quality they used and get depressed that you paid that much money for crappy work,
OR
you get darn impressed with the quality of the work and way the parts were assembled and are a bit afraid you won,t be able to reassemble the whole deal back together again to the same degree of expertise unless you work very very carefully.
AND PRICE ALONE and the BRAND NAME is NOT necessarily, going to provide you with the better result,
but ID bet a good deal of money that you,ll be amazed at the low quality of parts and lack of care involved that I've seen in some of the cheaper bargain priced crate engines.
surprisingly
I've installed several G.M. crate engines that I was not overly impressed with, over the years and they ran just fine and are still running fine years later!
but I,ve also helps guys I know install engines they bought off the internet that we found had serious flaws and I've been asked to diagnose why some engines failed within hours of being started, the first time!
your fairly safe with a G.M. crate engine, but I would avoid any non-well known brand crate engines!
ON ANY CRATE ENGINE I WOULD SUGGEST pulling the oil pan and at least checking the oil pump, and oil pump pick-ups correctly installed and verifying the main cap bolts and rod bolts (or nuts) are all tightened to similar and reasonable torque specs and look over the clearances, (like distributor end play and timing chain slack, ) and visually check the parts quality, it will only cost you an oil pan gasket and may save you a great deal of problems.
Id also verify valve train geometry and clearances.
CRATE ENGINES
http://www.jegs.com/c/Engines-Components_Engine-Assembled-Ready-to-Run/10763/10002/-1
http://www.tristarengines.com/catalog/high-performance-crate-engines/gm/383.html
https://www.summitracing.com/search/part-type/crate-engines
http://www.shafiroff.com/
http://www.tristarengines.com/catal...-engine.html?gclid=CIiE06P8j9MCFYaIswodlq8Ewg
http://www.chevrolet.com/performance/crate-engines
http://www.speedwaymotors.com/shop/crate-engines~6-10-344
http://rehermorrison.com/
http://www.herbertcams.com/herbert-cams-crate-engines/
http://www.proformanceunlimited.com/home3.html
http://www.jasperengines.com/crate-engines
http://blueprintengines.com/index.php/products/bp-gm-crate-engines-landing
http://www.gmperformancemotor.com/category/ENG.html