Basic get-it-running-reliably stuff is at the top of the list; tune-up parts and technique suggestions in
this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted
here for free download. And here's the procedure for
valve adjustment.
Safety is next up. I'd put in proper seat belts. Involved but not impossible in a car like yours. If you're not keeping the original seats, the easiest and best way forward is a set of Chrysler Sebring convertible seats with their built-in 3-point belts. Putting these in requires some electrical work; see
here. If keeping the original seats, I recommend
these up-to-date, reputable-brand ECE-approved 3-point seat belts (linked vendor is reliable; I've been buying there for a decade; their eBay store is
here). More info on belt selection and mounting is at the
maker's website. If I needed mounting hardware, I'd buy it again
from Wesco (and their page has good illustrated write-ups on how to install belts in pillarless cars like yours
here ), but the Securon belts are a much better-designed product than anything Wesco carries.
There are also bench- and bucket-seat 3-point belt setups available from
XV Motorsports, but I am hesitant to recommend or use them until I have more than a one-line say-so from the company that their belts actually meet the relevant safety standards; discussion on that matter is
here.
Unless the brakes are newly (or almost newly) redone, I'd put them near the top of the list for upgrade. 9" drums at all four corners were adequate for the original lightweight '60-'62 Valiant and Lancer, really not adequate in today's traffic on the heavier '63-up cars. LOTS of options for disc brake upgrades; ask for advice as a separate thread.
Good shocks (at least Edelbrock IAS, preferably Bilstein) and good tires (not from China) go without saying.
Of course, being me, I would put in
better headlamps (Cibie H4s if you want good but costly, GE Night Hawk H6024NH if you want decent and cheap but not very long lived) fed by
relays, and would also upgrade the car's other exterior lights (see
here).
Then after making the car much less inadequate to drive in today's traffic, I'd
then turn my attention to more extensive performance upgrades. Perhaps a 2bbl intake and carb (not entirely trivial on a '64 due to throttle linkage configuration, but certainly not impossible, see the
parallel 2bbl setup article -- photo documentation of a very well done such conversion is
'62 Super Six - a set on Flickr. And a nicer exhaust system with 2¼" headpipe. Stock manifold is fine,
Dutra Duals are better.
I lost count, are we up to or past 10?
