Auron,
It sounds like you are looking for, or at least open to some opinions, so here are a few:
A>A GOOD headlight relay setup is a good idea all the way around, considering that the nearly 40 year old wiring/headlamp switch (which has almost certainly deteriorated a bit by now) was barely adequate for the original style headlamps, and a definite requirement for even modern halogen lamps. Once you have a sufficiently robust relay system, whatever way you want to go for headlamps is up to you.
B>Your gauge/instrument setup/package is already just about the coolest of the lot for that year, so stick with it, make it all work correctly and spend the corresponding saving$ on other more critical and/or fun/cosmetic/go fast issues.
C>I personally feel that a rack & pinion setup is money and hassle poorly spent in this car. You already have the benefit, in that year, of an integral power steering box (that could be tricked out a bit if desired) and the only real gains

notnice

from a rack & pinion will be added header clearance issues, wider turning radius and added hassle/expen$e. You could do a WHOLE BUNCH of the many, many available suspension/steering/handling upgrades for the price and aggravation of the R&P and still have $$$ left over, giving you a lot more bang for your buck.
D>Switching to a stick is, IMHO, a definite addition in the "FUN FACTOR" zone! Seriously do your research before diving into this! Once you have the pedals swapped (pretty easy stuff) and decide whether to use cable, Z-bar linkage or hydraulic (my preference) for actuation, a T5 is pretty much a bolt in with few issues, a beefier Tremec is not too tough and may or may not require transmission tunnel mods/massaging, in your year and a T56 (which I believe is much less sturdy than the Tremec) will likely present the most fitment issues.
From the pics, I see there are already headers on the car, which leads one to suspect there may be other mods to the engine (possible cam/valve train, etc) so I would get it running as well as is possible with what is currently there for an engine and as long as the engine runs well, drive it like that through your other mods and THEN decide what improvements in performance are applicable for your use/driving.
Just My Thoughts,
Gene