Dennis,
When all is said and done, you will be happier with a custom ground cam, ground for your particular expectations and engine. There is an epidemic in the automotive aftermarket right now of camshaft lobes being destroyed by poorly made lifters. So buying properly sourced parts is a very important detail to be aware of, also.
Give Mark McKeown of MME Racing a call. He is very experienced with 351C engines, has Pantera experience too. He can grind you a cam you can have confidence in, and you'll find the price difference is minimal. The phone number is (301) 246-9225. The website is
http://www.mmeracing.comregards, George