thats a tough question..I dont know about the tri powers, Thers a gentlman named Bill Hanlon who really knows his stuff and has access to parts manual.

When I answered I was only thinking in terms of the four bolts that hold the valve cover on..

I have several GMC/s with the factory Pontiac V8's Thier valve covers are plain without the script too

also if you search all the 55-58 pontiac stuff some where there will be a reference to safri larry and or a website of his that deals exclusively with the mid/late fifties pontiac stuff

Plus lots of resources on POCI