If that ground on the firewall under the 15mm heaDED BOLT IS NOT BARE METAL CONTACT, AND/OR GHE STRAP IS NOT MAKING CONTACT AT THE HEAD, YOU WILL HAVE FITS WITH THE 2.5.
Just get the parts from an XJ.
This is one of those situations where free stuff or stuff you have laying around is not a cost effective route in time, money, or both.
HO exhaust manifold on Renix:
If you want to use the HO exhaust manifold, you must go with an HO headpipe and screw your O2 sensor into that headpipe. Standard Renix harness is plenty long to do so.
A bung can be welded into the HO manifold to accept the EGR tube also.