Cheap 318 performance mods.

Calhoun, first is what is your intended end use? Do you mainly want a Cars and Coffee cruser or something with more zip. When building any project you need to have an honest conversation with yourself.
Self, what have we got to start with and where do we want to get to for a completed project? Now what steps are attainable where as we/I progress we/I do not have to take stuff apart or replace something already bought and installed.
I would get to know and join a local car club. In most the friendly kidding between Mopar, Chevy and Ford guys is just that, friendly kidding. You will get to know guys that know engines, transmissions, body work and interior. Many times you can barter your talent/time to get help with some portion of your project. This can save you a ton of money or heartache.
Check the body over real good for signs of hidden rust and possible accident damage that was not repaired well. Best to find it and repair before installing the drive train and having to remove it again for access.
With intending to run 3.23 gears, plug your ears with those that are telling you that your only source to bliss is a hi stall converter. Cruising speeds with those gears will let the converter slip constantly and not "lock up". This is different than a lockup converter.
While the engine is out check it over for signs of leaks. Check for a rear crank seal leak or front pump seal leak on the trans. Easy to split them apart and replace now. Might be good insurance to just replace the pump seal and rear main now.
Intake manifolds, carbs and exhaust being external parts are fairly easy to exchange any time. Heads are a little more involved but not by much.
With that in mind, I would consider the cam swap now with the engine out and lots of room. Factory cams in the 318 2V, the Chev 305 and Ford 302 had about 195° @ 0.050" and 0.390" valve lift. These engines perk up well with a cam of 204° to 210° intake duration and 0.425" valve lift. Getting into the 220°@ 0.050 lift intake on the cam still leaves you with good torque for the street and good drivability. With this you could be looking at closer to 0.475" to 0.500" valve lift. Valve covers and rocker shafts have to come off as well as the harmonic damper and front cover. Get the cam kit with lifters and a good double roller timing set. You can build a piston stop by cutting an old spark plug at the crimp that holds the ceramic in, cutting the ground off and pushing the ceramic out. It is a bit of a fight. Grind a bolt to have a round end that fits snugly into the plug body and sticking out about 1/2" to 3/4". To degree the cam you install this in the #1 plug hole to stop the piston as it comes up. Note the degree wheel reading. Rotate the opposite direction until it stops and note the degree reading. Half way between is true TDC. Adjust the degree wheel so it will indicate TDC properly and recheck. The piston should stop the same number of degrees before TDC and after. You may need to tweak the degree wheel a bit until you get the same reading BTDC and ATDC. Now you can remove the piston stop and used a dial indicator to verify the cam is installed correctly per the supplied timing card.
If you have a flat tappet cam be sure to use the supplied lube and a breakin oil. If it is solid lifters, reinstall the rockers and adjust the lash. Hydraulic should be fine.
With #1 at TDC you can put air into the cylinder to install checking springs before installing the rockers on #1. You can use the dial guage to check piston to valve clearance at 15° to 10° BTDC for the exhaust and the same ATDC for the intake. 0.080" required for the intake, 0.100" for the exhaust.
Now if you got new valve springs you can replace them rolling through the firing order at TDC for each piston with compressed air holding the valves closed.
You can replace the intake now or later. If you chose to replace the heads now, replace the springs with the heads off. Put the checking springs in #1 of the new head to check piston to valve clearance. Use the modeling clay method.
Have fun and good luck.