The Temp guage has a barrel on it that fits right into the head. Did you get this out without breaking the line? If so, I believe the 401 heads have a plug screwed into the same general area on the heads but wheather or not this will fit into the 401 head is questionable.
The oil pressure guage is manual and bolts into the rear of the engine block. You probably have to extend the line for the 401 to the front of the block. You probably should put in a manual guage at first just to get a comfort level with the actual temp and oil pressure value as I don't believe the 54's are graded with numbers.
The Ampmeter is actually in the wiring harnes with the starter, if I recall correctly, so this should work when you hook up the new starter.
JD
_________________________
John C. De Fiore BCA # 3757
56 Super 56R
69 GS 400 Convertible
69 Electra Limited 2 dr.( well, no longer limited although still unique)
95 Riviera Supercharged (sold)
06 Lacrosse CXL
Doing my part to stimulate the economy!
Member of the UPSTATE NY CHAPTER
check it out at
http://unybca.skyphix.com/