No personal experience with them, many times while watching the program, Engine Masters, you'll hear them mention that a whole engine, or certain parts such as cylinder heads were sourced from "Blueprint Engines".
They have their own line of "New" cylinder heads for popular applications (SBC, LS, SBF). From their website they've been in business since 1982.
I do know while they offer daily driver engines, they also offer performance engines such as mentioned above.
If you search on the web, they come up as reputable.
Being in the auto repair business for decades, I've heard more positive about them than negative.
Warranty is 30 months/50,000 miles.