what smallblock (with freedoms)

If you need the low-end then the 360 would definitely be a good choice what with its longer stroke. However if you can find one a 6.1 Hemi would hands-down be the most potent "small-block" to use. You could push 500-550 horse easy, N/A to boot. Only thing would be price, as they might not be very plentiful in your part of the world and they're still pretty darn expensive over here (the 6.1, not the 5.7L).