Hi,
If you use a thinner head gasket(Cometic .30) you need to check the base circle dimensions of the 54s, made that mistake last year,it is not just the lift at TDC you need to wory about, if the base circle is the same as the HD255s
then you will need adjustable push rods, this very problem cost me a set of cams and lifters, they were both destoyed.
I changed my 255s for Zippers 575s but I did not check the base circle dimensions against that of the 255s and because the base circle was larger, it did not allow the lifters to unload properly, and the lifter roller/cam lobe
over heated and then the lifter rollers flat sided which then damaged the up ramp on the cams.
Oh sh*t wont make that mistake again.
Take my advice use adjustable pushrods.
Good Luck.