Thank´s again Man in the car for great information!That is correct - the strengthened oil rail wasn't available until early 2006; nearly a year after the last MG Rover engines were built ('New Take-Off' simply means that the part was removed from a part-built car or part built engine on the production line after MG Rover had gone bust. The parts had been fitted, but not used).
I am not sure what precise difference there is between the genuine MG Rover/Land Rover one (which I think will have been manufactured by Hyundai), and the aftermarket one which appears from the picture to be made by BGA. BGA are a perfectly reputable supplier of aftermarket parts so I would not think there should be anything wrong with really. However, if it was my car, I would tend to favour the genuine MG Rover or Land Rover supplied parts I think (purely a personal choice and based on no particular evidence of knowledge!).
The oil rail bolts to the underside of the crankshaft ladder, so there will be no need to remove the crank ladder or crankshaft to replace the oil rail, and the only other thing that you will need will be the anaerobic sealant to apply between the new oil rail and the crankshaft ladder. The same sealant can be used to reseal the sump to the bottom of the block (Loctite 574 is the one that has always been most recommended around the forum).
I would also be inclined to use the 6-layer N-series gasket along with the strengthened rail and higher tensile through bolts (available as a complete kit from XPart agents under part number ZUA000531, although quite expensive at nearly £200). You would also need to check that there is sufficient stand proud of the cylinder liner above the block, and that the liners are of even height above the block to reliably use either of the multi layer type gaskets - probably 2 to 4 thou measured using a metal straight-edge and feeler gauges.
NB: the SAIC/N series gasket and bolts have a different tightening sequence from both the original K series elastomer gasket and the first type Multi Layer steel gasket (MLS - often referred to as the 'Land Rover' gasket as it became available through Land Rover first) 9.8 tensile bolts.
SLS/Elastomer gasket and 9.8 bolts = 20 Nm + 180 degrees +180 degrees
MLS ('Land Rover') gasket and shim with 9.8 bolts = 20Nm + 180 degrees + 180 degrees
SAIC/ N series gasket and 10.9 bolts = 20Nm + 180 degrees + 135 degrees
I don't think I would bother with the PRT thermostat - much is made of it in some quarters, but MG Rover fitted it as standard to the 75/ZT 1.8 turbo and to late MG TFs, but there is no evidence that it actually made any measurable difference - the head gasket failure rate remained similar to that of engines with no PRT.
I wouldn't take much notice of people who go on about 'thermal stress' or 'thermal shock' with regards to the K series; it really isn't an issue, particularly with regard to the head gasket. During the development of the K series, Rover couldn't get the K series head gasket to fail at all using the industry standard thermal shock test, and had to devise an even more extreme test to cause the K series gasket to fail. This suggests that the original K series elastomer head gasket is rather less affected by thermal shock than most 'conventional' head gaskets.
No I have ordered the ZUA000531 kit from Rimmer bros. I skip the PRT termostat so I´m saving some money and work too .
No it just to wait, I live in Sweden but in best case I have the parts before next weekend and can fix the car then.
Thank´s and best regards!