I hadn't heard of him, but apparently he's a Mustang guy. from here:
http://www.seanhylandmotorsport.com/about-us/
"Sean founded Sean Hyland Motorsport in 1988. As Sean became immerse in developing the 4.6L engine in the mid 1990s, time commitments forced his own Motorsport adventures to take a back seat to his business, Sean Hyland Motorsport.
Sean is still at the forefront of 4.6L Modular V-8 development today, and he’s justifiably proud of his achievements. Most notably the 4.6L and 5.4L engine block that he designed for high-performance applications. Today, Sean is involved with making Mustangs go faster every day, and he’s also the resident racing expert on Speed Channel’s Sports Car Revolution."
No mention of him building a Mark VIII on his website anywhere though..