(A) height: I think there will be clearance.
(B) Not sure yet: two differing schemes, if so.
Remove the oil pan and decrease its depth at the front, as much as possible, and/or move the engine back.
That might entail opening up the transmission hole in the firewall, but that’s not a biggie to do.
Going to use the stock manifolds, and gutted cat, into a single pipe, out the driver’s rocker panel.
EDIT: Took a tape measure today , before “sa bluste kalte vind” began, and height isnt an issue: Ill likely have to modify both the oil pan, and the custom x-member, to make it so the engine will fit. The V6 is 24 inches long, and the Jag is 27 inches. I’ve got a spare one (locked up: anyone need a SIII head?) that I can fiddle with the pan, to help it clear the extant cross member.
In about 6 to 8 weeks time, I can get the body off, the V6 out, then start trial-fitting the XK.