Yes, use your '55 rocker assembly then.
I've not seen any rotators used before. Nothing special in the shop manuals I've looked at either. My 261 didn't have any.
The cylinder heads are all the same from 53-62 except for temp sender size, chamber volume, valve guide installed height, and extra steam holes for the 261. There is nothing about any 53-62 head that would prevent you from swapping it with any other 53-62 head. The valve springs were a little stronger on the 261, and it may be possible the installed heights were different, but I would have to look into it further to be sure. I doubt it would really matter. I used the dual springs from Clifford and they are installed at a height different from stock anyway.
If in doubt, install at the specs for the year the head is. The date code is on the pass. side of the head.
Get a 59-62 shop manual and look at the engine section. It will show you very well what the changes were to the engine blocks.
The whole "drilled head bolt" issue comes from not understanding what the notes in the Master Parts Book said concerning its usage. It's really about the rockers, not the head itself. Use the right rockers with the right block, and it's a moot issue...
