Knowing a bit about the 318 engines, I would highly recommend switching the cam first. This is the carrot in the engines arse. A 360 cam or an aftermarket cam with about 210° to 215° intake duration at 0.050" lifter lift and about 220° exhaust duration at 0.050", 108° LSA installed 4° advanced. Most are ground advanced, so go with the timing card. You want 0.475" to 0.500" intake lift. Exhaust can be a bit less. This is the plan I would have when money is tight. This will perk it up even with the 2V carb and manifold. Then when enough money is put aside or a smoking deal comes up like at a swap meet or used, go for the manifold and carb. Then later think about headers.