Replacement Engine for an XK 140

[sjacobsuk]

A new member and owner of an xk 140 FHC. Unfortunately it has a Chevy V8 and auto transmission in it currently. I'm going back to Jaguar...and looking for some advice. The heritage certificat shows it was an SE, not "C" type heads, and BW auto transmission originally. I have £25k in it so far, a decent budget to spend, It has a decent body, interior and paint that I can live with, and don't want to end up with more in the car than it's worth. My goal is a daily driver.

I've been doing some research and it seems like I have three options: 1) find a matching G series engine and box so I am as close to matching numbers as possible and rebuild them, 2) find a period 3.4 engine from a Mk1 or mk7, (maybe even an runner?) and appropriate 140 box, or 3) go big and drop a 3.8 in it, probably from a MKII, and appropriate 140 box.

Which would you chose - 1, 2, or 3?

If I go for 2 or 3 some other issues have sprung up:
- Oil Sumps and Pumps seem to be a language of their own. And 140 sumps are scarce as everyone knew but me. Have learned the 3.4 oil pump changed some internal/external parts during the run, and that mixing an engine with another sump likely ends up with some pipework changes. Which engines would "drop right in" to a 140? Can you modify other sumps to fit... e.g. if I went with a MK1 engine I've been told you can cut off one of the sump "wings", close the hole, and it would work just fine provided you didn't mind how it looks from below. Any 3.8 engine sumps that would fit other than a 150?
- it would have to be a period or G series engine to have the mechanical tach takeoff from the cam cover (I've been told). If I upgrade to a later engine how difficult is it to get a working tach on a 140?
- Finally, I'm biased against the original moss box but maybe that's unfair. I understand OD is critical for cruising at reasonable rpms. Moss box with OD or upgrade to a 5 speed?

I recognise that's a lot of questions for first post but all opinions welcome. Hoping to learn from other's battle scars.

Scott