Hi Adam, I’m in the process of rebuilding my 1985 xj6 and will be putting a 1995 LT1 Gen2 small block in it. I have been at this build for 18 months and am happy to share what I have learned.
The front ride height is pretty easy (relative to other things) to adjust. There are “packing rings” stacked above and/or below the springs, they are just a tough nylon-type ring 1/8" thick. Adding or removing one equals 5/16" change in ride height. Another standard method of adjustment is to lower the bottom spring pan (seat) by placing spacers between the pan and lower A-arm; same amount of height change. My S3 came as a “glider” so ride height will be something I will address when it is all together. I have read posts that suggest the best looking ride height is one where the tire fills the wheel opening equally around, but depending on the tire size you use, that might not give the best ride height geometry.
In the back, there are fewer options to adjust ride height. Replacing bad shocks is probably the first thing I would do. Most all of the better shocks now are gas-filled and as such will exert 15-20lbs each of expansion force. 4 shocks then would be providing about 60-80lbs of lift to the rear without any other adjustments. If you don’t think that will do it, I have read that there are other springs with different ratings available for our cars, but opinions and success’s are all over the place.
Rear alignment amounts to adjusting the camber and that’s it. Adding or removing shims between the brake disc and inner drive shaft connection is how that’s accomplished. I read your post in the Series section and someone posted the front/rear alignment specs there. The front end aligns a little differently on these cars than modern American cars. Not better or worse, just different. If you don’t want to get neck deep in the science and procedures of alignment, finding a shop that has actual experience with the Jag setup would be important, I think.
You mention something about “ratcheting the car down” to do an alignment. Even in a parallel universe I can’t imagine what that is referring to. Again, as others have posted in the Series section, there are front/rear ride height setting tools that are specified in the Jaguar manual, easily made if you are handy. A copy of the Jaguar Shop Repair manual is a must if you intend to do any work yourself, which it sounds like your are, considering your engine swap.