160 hp
I think you mean taller pistons. Hope you changed to the 160 hp heavy wall piston pins.
The Ram STC for upgrading the E2D requires either nitride, chrome or nickel cylinders.
The A.M.R.&D STC for E2A does not require a cylinder upgrde. The engine remains a E2A, apparently with a supplemental data plate in adition to the original.
The E2D has the 0 235 front main bearings so it definitely does not become a D series.
As far as experimental there are people running 10/1 pistons in plain steel cylinders with two piece front main bearing.
Lots of information available on Lycoming group and by googling 150 to 160 hp conversion.