Just seen this thread & thought I'd relay my experience.
I have an XM coupe running a 5.0efi & 5 speed man.
The brakes, markdlowe is right on. I have the same setup on my car & it's really good. XA(?) dual master, bolted direct to firewall, remote VH44 booster up under the driver's side guard just behind headlights.
Had John Taverna chassis in Melb fabricate/modify an 8 3/4" Mustang diff to suit.
Engine mounts - don't use the CRS units
, engine sits too high & too far forward, meaning you cannot run an engine fan cos you'll cut your rad hoses off. Use the original 63 Falcon (US) V8 mount setup complete. Sits motor perfectly in engine bay & is a direct bolt-on as the US cars at that stage had identical dimensions.
Radiator - I've used an AU unit. Have to drill 2 holes in top of your front chassis rails to suit bottom pegs. Use AU factory upper mount brackets bolted to radiator support. By doing this you can use factory AU rad hoses, just shorten the ends to suit shorter XM/P engine bay. For a recovery bottle/air purge, used a remote mounted unit from a Camira (not shown in pic) mounted just higher on engine bay wall than rad inlet. I'm using the factory 5.0 engine belts & fan and all fits like a charm. The fan shroud is an XF unit trimmed to suit the AU rad.
You'll notice the shock tower braces modified. This was done when using the CRS mounts as it cocked-up the position of the engine & I couldn't fit the upper efi intake. With the US mounts this would not be a problem I think.
Relocated the battery to the trunk, to allow me to keep the AC compressor & PS pump "just in case" I go RRS & aiir-con. Air cleaner is a pod type mounted on engine bay side-wall.
Car is on the road & drives beautifully.
Hope this has been some help :)