Jaguar Repair: 86 XJ6 Distributor install, deg btdc, jaguar xj6

Question
I recently acquired a "new" distributor on ebay with the following description:

"YOU ARE BIDDING ON ONE (1) RARE VERY LIGHTLY USED LUCAS CEI IGNITION DISTRIBUTOR. IT IS LUCAS TYPE 45DM6 DISTRIBUTOR, PART NUMBER 41819A. IT IS VERY LIGHTLY USED! IT IS SPOTLESS INSIDE WITH NEGLIGIBLE WEAR ON THE ROTOR & CAP. I IMAGINE A MECHANIC INSTALLED IT ON A CAR TO CHECK AGAINST THE ORIGINAL. THIS WAS A COMMON OCCURENCE. IT FITS THE FOLLOWING;

JAGUAR XJ6 4.2 SERIES 2 WITH FUEL INJECTION, ENGINE # 8L67735 on.

JAGUAR XJ6 4.2 SERIES 3 (AUSTRALIA) TO 8L87450.

Because this item was in good shape at a decent price, I bought it. Now I have two questions:

1. Do you see any issue with it fitting in my 4.2?
2. What is the procedure to install this distributor? I have done my Chevelle, but not a Jag.

I have read on forums that the timing is 18 deg BTDC, is that right?

I have also read that there are different size flanges on distributors for this car. Does that sound right as well?

I would like to install this new distributor in my car and keep the old one as a spare. The car runs fine but I would guess this would make the car more reliable. What are your opinions on this idea?

Answer
Hi Scott,
I have never tried to install a Series II distributor on a Series III but if the plug connector is the same and can be plugged into the amp. I would guess it should work. The 45 DM6 distributor was used on all 4.2s  As for the mounting flange, they are removable so if they are different you should be able to switch them. I thought they were the same but I can't depend on my memory any more.
I show 17 deg BTDC but that would be picking fly stuff from pepper and I found that different cars (All Series III cars) sometimes need a different timing. Not by much but just a little to make them run correctly. This is the only car I ever found that the timing may need to be altered to make it run right. I normally tell everyone that factory timing is a must unless you have modified the engine.

Installing should be easy as the shaft has a blade that is offset and can't be installed 180 out. Firing order is 153624 as all inline 6 cylinders are. Jaguar calls the rear cylinder #1 but it don't matter if you want to call the front cylinder #1, that's ok as the firing order is still the same.
Howard