If you are using stock iron heads, port-matching the exhaust will make it feel like you upgraded the cam.

 

Put the rear on jack stands. Put the trans in neutral. Carefully rotate both rear tires exactly one turn, and count the turns of the driveshaft. Three-and-a-half turns would be 3.50:1, etc.

 

mild port work and maybe a bowl blend on the heads will help some, im a big believer in no doing too much more to the heads past that though, once you get into getting alot of work done on the heads with the money youll have spent you could have easily just saved a little more and gotten a good set of aftermarket heads, i agree on gettin the front disc brakes and regearing first though, then worry about the motor

 

The head work I mean could be done by anyone capable of removing the heads, in two hours or less.
Cost for gaskets and a cheap die grinder under $100. These exhaust ports were undersize to begin with, and addition of bulges for the pollution equipment was essentially sabotage, as though Chevy did it to them.

The amazing amount of flash around the edges is stunning, but the "nose" inside the port, at the worst possible place for roughness, let alone this huge projection, just kills performance:



There is plenty of room for improvement. In the 60's-70's Crane made "Fireball" heads using Ford replacement castings as the starting point. They removed an amazing amount of material from the exhaust ports, so much that special headers were required:

 

oh i agree that a little work with a die grinder to clean up the ports and gasket match them is definatly worth it, i plan on doing it on my basically stock 302 untill i can save for good heads, i was just stating not to put too much money into them as far as having machine work done as by the time you pay for alot of machine work youd be well on your way to a good set of aluminum heads

 

Rotated tires 1 full turn, driveshaft turned exactly 1.5 times. while under the car i gathered a little more info. no bolt on rear-end cover, front of rear end unbolts.
There is also a tag , tag reads
WCZ-F 3DC
3.00 8 931C
the bottom 3 could also be an 8, its hard to tell

 

OOPS!!! My bad, I only turned 1 wheel the first time. It turned just under 3 times, maybe even 3 . it was close.

 

It's an 8" with 3:1 gears and 28 spline axel shafts.

 

What needs to be done to upgrade to 3.55 gearing?

 

spend the money on new alum heads if you already have a roller motor, twisted wedge or afr 165's.