It took me minute to think. When i first read this I thought you were doing a build by using those parts. Now I see you bought this car with supposedly these parts in it.
the cam and heads are not well mated together in my opinion. Pistons are a name brand but you cannot be sure at someone just name dropping. You need to see the paperwork on them.
Assuming the stock intake is on this car and the stock rods etc the carb is probably not too "small" as the intake is choking the whole system down.
If you want to do the motor right I would plan on starting fresh. Ask yourself what you want out of this car? Cruising with some snap over stock? 1/4 miles tire smoker? track car for gymknhana's and some club race days?
are you trying to keep it as stock as possible with a cat on it etc?
or are you going to not worry about that sort of thing?
then decide on whether to go with a high rev 350/355 set up or a big torque 383... once you decide on what you want then that will determine what a good build would be.
Saving the heads and other parts should be your last idea... they are not as expensive as one thinks and if you build it right, then you will enjoy the car a lot more
just my humble two cents
these are wonderful cars when done right