Upgrades to my stock 273 67 Dart GT

if you don't already have electronic ignition with a properly curved distributor that should be number one on your list with a bullet.

cheap, easy and compliments every modification you'll undertake down the line.

after that, a cheap dual plane manifold-- you can pick up a performer new or used that will work great. obviously, stock 4bbl manifolds are out there as well and while they're heavy they do the job damn well. obviously there's other aftermarket brands out there such as weiand and offy, but the performer (or a stocker) is going to be the best match for your motor.

small 4bbl carb-- 600~650cfm is what you're looking for. a used carter afb/edelbrock are in abundance and have tons of tuning parts and are dead simple to dial in. a carter avs2 would be an excellent choice as well. if you're willing to learn and put the time in, you can reap rewards with a spread bore carb such as a thermoquad or q-jet, but know going into it that the learning curve is steep.

on exhaust, a true dual system is great for uncorking the power. but exhaust is one of those things where you can pay a little bit of money for something that works, or a lot of money for something that works really well. cheap headers hang low, bang all over everything and are a pain to install and rust out. expensive headers tuck up tight, have clearance, install easier and tend to last longer. and while headers will pick up power everywhere, this being a lower performance street car you're not going to see massive gains for the money spent, so it's kind of a personal choice on headers vs. keeping the stock manifolds and just running duals.

i understand budget and skill dictates a lot of upgrades and modifications. but you should be able to do the most basic of hot rodding upgrades on a beer budget with basic hand tools and greenhorn mechanical skills.

keep in mind, changing to a 4bbl means modifying your transmission kickdown linkage as well as your throttle cable/linkage-- this topic has been covered extensively here, so use the search function.

also, there's nothing wrong with keeping your 273 2bbl. get it set up with electronic ignition and a nice curve, throw a tune up at it, get everything dialed in, pop for dual exhaust and see how you like it. you may just be surprised!