Upgrading parts for racing ?'s

[low&slow]

So I can't seem to find a good decently priced radiator repair shop around this new town I live in, so I was just going to buy a new aluminum one.

My question is, What size of radiator should I buy?
I don't really want to spend more than $220 on one.
I'm also buying from Summit Racing.

A little info on my setup.
Automatic Transmission.
V8 Big Block.
No power adders.

The second question I have is, What harness should I buy as well? And if possible, can I buy one from Summit Racing that is DOT approved for drag racing?

Third question, Am I better off getting a new windshield or to buy plexie glass? The reason why I ask this question is because I do plan on chopping the top soon and I don't really want to buy a window now and then have a new one built later on. As with plexie glass I can just cut it down to fit the chop.

Also I'm hoping to get enough info because I do want to have the first and second questions ordered by Sunday night at the latest.

Thanks in advance.