Martx I have the same engine in my TR4a, and have done basically what you are planning.
First, since you are putting in liners and pistons you obviously are going to have the engine apart, so I feel a fast road cam would be worthwhile, and you may need to replace your cam and lifters anyway.My cam is from Kent cams, the Sprint 88 grind, might be a bit too much for most people, they have milder ones, as do Piper cams, Web cam in California etc. (I would advise against regrinding your stock cam as it is symetrical, a compromise made presumably to control production cost, modern cam designs give different intake and exhaud\st timing and perform better.)
Second, you are increasing the compression anyway by increasing the displacement; if you had 86mm pistons you are going from 2138cc. to 2188cc., about 2.5%, so if you had 9:0 to 1 compression you now have 9.2 approx. If your pistons were 83mm. you are going from 1991cc. to 2188, an increase of nearly 10%, raising your compression from 8.5 to 1 to about 9.35.
My advice is to take the head to a machine shop and cc. the combustion chambers so you know where you are now, as the head may have been skimmed as part of a previous rebuild. You also need to measure the depth of the pistons below the deck height and allow 1mm or 40 thou for the compressed thickness of the head gasket.
A reasonable ratio for pump gas is 9.5; mine is at 9.75 and I use 94 octane Sunoco.
Keep in mind that a moderate power increase is fairly easy and not too expensive, a really big increase will be very costly and make the car less driveable in traffic.
I am still using SUs on my car, with a range of needles, and find they work well for a car in "fast road" tune, as the English refer to it.
Good luck with your project.
Simon, WOFTAM Racing.