383????

[jethro2996]

First, bear in mind that you can buy an engine built as cheap as you can do it yourself (I say that at the risk of catching some flak). If you like to build and have the skills/tools/help/shop/advice by all means have fun. I prefer to build my own, it is my therapy for life. However, if this is a one shot deal and you don't really plan on building more in the near future or don't have the time/space/ capabilities/tools, it might be just as easy/efficient to buy one with a warranty and go. Again, I prefer to build my own but I value the time I spend in my shop, for me it is as much fun as the race itself.
Your heads are going to be a coin toss. Here is what I know, use it as you wish. Cast heads are cheaper, do almost as good as a job, and last forever. Aluminum heads are about half of the weight, easier to repair, and will have slight flow increases. They also look better. I am presently building a chevy 412 and originally wanted aluminum but have since changed my mind and will go with cast. The reason is that the heads that I want are about 400 dollars cheaper in cast than aluminum. I can now take that 400 dollars and spend more on an electric h20 pump, better radiator fan, and better tires. The point being is that while 400 dollars in aluminum heads might get another .05 of a second, the 400 dollars will get me considerably more in better tires and accessories.
As far as pro-comp goes, I have yet to find the bottom to that answer. I hear/read many conflicting stories from unreliable sources. They cost about as much as good cast heads from reputable manufacturers and you will know exactly what you are getting with a name brand.
I hope this helps.