And thereby hangs a tale . . . .
Now, I have done what you propose--I cut the pilot from a PW C&O FA shell, used the metal reinforcing plate that one can buy to repair a cracked pilot, and a little bit of paint and glue, to make an 8351 with a front coupler.
BUT: there is--or at least WAS--at least one 8351 with a front coupler from the factory. Christmas shopping season, 1976. Sears Roebuck, Northwest Plaza, St. Louis County, MO. I was 12. My grandparents took me Christmas shopping looking for Lionel trains to add to the one Sears Lionel set and the one Sears Marx set I already had. But it was 1976, and there wasn't much to be had on the shelves--a few pieces of track, a few odd pieces of rolling stock, a set of yard signs: no sets left. But in one display cabinet was a pair of Bluebonnet Santa Fe Alcos, being sold AS a set, and one with a coupler through the front pilot. At the time, of course, I had no idea this was anything unique, but I did want the pair. You see, they went perfectly with the Red Warbonnet Alco I already had. As I studied those engines, I knew I could recreate a train just like the real ones with MORE THAN ONE ENGINE! I was hooked!
Alas, my grandfather had other ideas. He was partial to Lionel, but he was miffed there was no full set--cars and all. So he and Grandma pulled me out of Sears, a disappointed boy, and went to Penneys where I ended up with a Tyco Chatanooga Choo-choo and a ten-year, ill-starred detour into HO.
I never saw those Alcos again--the next time we went to Sears, they were gone, presumably sold.
Over the years, people have tried to convince me that I didn't know what I was looking at, that neither one had a front coupler or that the pair was the D&H version. But I know what I saw--I was 12, but I was not ignorant--and there was at least ONE ATSF Bluebonnet Alco with a front coupler being sold NEW by Sears during the fall of 1976.
And I would pay handsomely to own it today.