well sapphires never had a t35, do you mean the big turbo escort?
(sapphire 4x4 and escort big turbo heads very similar/same i think)
i know the cam covers are totally different and cannot be interchanged...
different camcover gaskets as well
t25 head has the coils under the camcover
same head gaskets and valves can be used.
don't know about the camshafts. anyone?
water connections different too

i would like to know the difference too as i bought a brand new eecIV bare head off ebay