The best you’ll ever get out of a engine rebuilder is going to be a refurbished engine , they’ll install your cam and top-end parts but most of what they sell is only inspected as sight unseen, ( to make it affordable ) and if it turns over they put lipstick on it ( in your choice of color) and call it a day.
One of the red flags to let you know when you are dealing with a remanufactured service is the stipulation of a heat “tabs” installed that distort in order to detect abnormal temperatures for warranty purposes.
The whole reason for them to mention this is because this is the conditions of warranty for them to follow from the contracted refurbished engine supplier….
A half decent rebuilder ( engine machine shop ) would make certain the recipient vehicle’s cooling system be more than adequate to handle engine break in temperatures.