I have a new set of ACL duralite RP4101 unleaded +20 thou pistons originally bought for a XF 250. I know the gudeon pin is the same with the right bore is there any reason they won't do the job?

a 20thou over XF piston is the same bore size as an 80thou over bore in an EF.
standard bore for an XF is 93.47mm
standard bore for an EF is 92mm
a 20 thou over XF piston is 93.98mm

and the compression hight is wrong.

compression hight for an EF piston is 35.83mm
compression hight for an XF piston is 38.862mm

Damn, not gonna go then but thanks for the info