There are quite a few people on the UK forum who have modified the 6 cylinder XK powered cars. The answer to your question comes in two parts:- an ignition map and a fueling map.
There are plenty of ignition maps already posted. You want to chose one that matches your camshaft as a racing cam will want to idle differently from a street cam.
The fueling map is something you can usually make up yourself if you have access to a wideband and user configurable software.
There is a lot of good advice on the msextra.com website which translates over to any car, not just a Megasquirt (“MS”) fitted car. The key to a lot of this is to have datalogging capability, which on a MS car is supplied through the Megalogviewer free software. The paid for Megalogviewer HD version (about USD50-70 iirc) allows you to plot graphs and tables of anything (or any data derived from a formula thereof) to aid your understanding of how the engine is running.
As an example, here’s a graph of how open the throttle is versus the reading taken from a sensor on a ported vacuum tapping on the throttle body during a test drive. The 100% load line shows that WOT is achieved at just 40% opening at 1350rpm, i.e. the engine has all of the air it needs at that speed and opening the throttle any more simply makes the
revs go up.
This graph shows what the air pressure reading is at the ported vacuum port on the same test drive (at sea level). Normal air pressure is 100kPa and 100% vacuum is 0kPa, so when the throttle was shut on the first graph (a reading of 0), then you’d expect it to generate no vacuum as the reading is 100 because the port is on the airbox side of the throttle plate.
This sort of capability gives you the tools to answer “what the engine was doing” and the basic log graph tells you “when”, i.e. cause and effect. That’s how you’d dial out resonances and flutters in your current maps.
Essentially, go for a system that allows you to datalog your engine, if you want to know the reason why it does what it does. Without that, you’'ll always be paying someone else for every mistake they make as they learn rather than you.
kind regards
Marek