I think I've read somewhere that he cut the center out of the merc hood and welded it on the stock 54 ford hood. I believe the merc front end is a bit longer than the fords. Nice custom touch though.
Mercury parts car, scroll down to member Dean Adkins: https://www.facebook.com/groups/193973717381378/?fref=nf
Over on the '54 Club of America site we have a member ( Ronny) from Norway using the Mercury hood on his '54 Ford,it bolts on but is longer in front than the Ford hood. HRP
He actually used the entire Mercury front clip,he posted a lot of pictures in the 1954 group archives. He dealt with a lot of rust issues in his build and showed a lot of skill with limited resources it's not so easy to find parts overseas.
Merc's wheel base is 3" longer than the Ford, I have heard but don't know for sure, but they say it is from the firewall forward??? Also the Merc's Scoop was functional in that it added clearance above the engine... If that makes a difference to anyone.. Be glad to measure anything I can off my Merc