Engine swap

I have a 2006 Subaru Forester with the ej253
naturally aspirated it has the avls. The block
is cracked. I purchased the motor out of a
Subaru Outback but it is an ej251 and does
not have avls. I know I must swap the
crankshaft reluctor wheel or gear as some
call it and the driver side camshaft gear
along with the intake from the ej253 over
onto the ej251. My question is this the
wiring harness that goes to the ej251 in the
outback is way different than the wiring
harness in the Forester due to the avls. Do I
have to put the heads from the ej253 onto
the block of the ej251 in order to make it
work or can I just simply put the intake and
Cam and crank gears on it along with the
wiring harness and just leave the parts of
the harness that go into the avls system
unplugged rather than putting on the heads
from the 253. The only reason I ask is
because I'm pretty sure one of the heads on
the Forester if not operating correctly. I
guess pretty much the question is how can I
do it and make it run these incidents are like
Legos and they can be built several different
ways some say that all I need is to switch
the intake Cam and crank gears and wiring it
harness over and just to tie off the parts of
the wiring harness that would go to the
heads and the avls. Some say I must put the
heads from the ej253 on to the ej251 as well
I hope that is not the case