It depends on what you are trying to get out of your 355. Exactly what are you looking for? What type of vehicle is it going in? How much does it weigh? Will you be using it on the street, strip or both? What intake and carb? Headers? How many RPM do you want to turn?

I am guessing that you want something streetable and good for pump gas.

You need to know more about the cam than the .501 lift. Find out exactly what it is if you are really interested in using it. For the street, find something that has around 220 degrees duration at .050 and a 110 degree or so lobe seperation. Anything less than 110 will guzzle gas. .500 or less lift will work OK if you use good single springs such as the Z28 ones or aftermarkets.

The 882 heads work fine on the street, but are unsuitable for much else. They can flow well for a stock head, but are thin and have pretty big chambers. You can port them some, but I wouldn't spend too much time on them. Heads are where you make the power, period. If you want big numbers, buy good heads. If you want stock type performance, use the stock heads. For Cast Iron heads, either port the heck out of yours or bolt on a set of Sportsman II's. Whatever your budget allows. Those 882's are the weak link in your motor so far.

With the deck height you have set, you will need to use a steel shim .020 thick head gasket to get proper quench. You are looking for about .035". A thicker gasket will hurt you.

I can't make a suggestion on the converter until I know the gear ratio of your rear end plus the answers to the questions above.

The bottom end that you have will withstand about 450hp. If you plan to try for more than that, your rods and crank will have to be upgraded. Make sure you run a good oil pump such as the M55A Melling.