I think if you wanted some HP and some pretty surprising performance I would do several things....
1. Cam swap (nothing crazy just a decent flat tappet with some added lift and duration)
This is the most important thing because as stated before this is set up for TQ only.
2. Shop around for some cheap BBC heads...Just about any oval port heads will support 450 hp. Just watch out for peanut ports. Deals can be found anywhere on these "mediocre" oval port heads. Ideally you will find some with 100 cc or so chambers to bump up the compression a bit like these...http://cgi.ebay.com/ebaymotors/BBC-C...item2c5386b86b
If you do these two things with a little help from your friends you will have less than 800 bucks in this motor and it will run pretty dang good. Once you have these things you can drive the car around with the stock intake and carb and when you get a little more cash throw on a cheap intake and find a 750 carb and it will really wake up the whole package.
If you can't spare 800 bucks to do this then you might as well just forget ever considering a big block, cause this is as cheap and quick as it gets.