Here is the definition of custom built as defined by websters

Main Entry: cus·tom–built
Pronunciation: \ˈkəs-təm-ˈbilt\
Function: adjective
Date: 1925
: built to individual specifications <a custom–built house>

There you go "built to individual specifications"

just maybe there is a reason the 350 chev is a popular choice. Using a 350 could be considered mainstream but how you install it, the add ons, and paint work can set it aside. I have searched for 350 rangers and not saying it is not already out there, but mine may be different since it will use all the 5700 vortec injection along with a 4L80E trans and the serpentine accessory drive with A/C. Graphed a chev cluster in to the ford so I would have the digital PRNDL readout. The whole thing is OBDII compliant. But if you believe that out of catalog bolt ons are more "custom" than one off hand made parts than cheers my friend, I will be at the end of a plasma cutter while you are at the end of the line at the counter of your local speed shop turning pages in the "custom" catalog