There is nearly nothing available off the shelf that will give you big power gains.

Atmo - fit throttle bodies and a decent management system, big valve head (http://www.cncheads.co.uk/ford_puma.html), 4-2-1 manfiold, cams etc should see around 180-190+ BHP.

Turbo - I'm running around IRO 270 BHP at the moment from my 1.7, but it is a complete one off developed by myself for sprinting.

Budget depends on how much of the work you can do yourself and how much you have to ship out to 3rd parties. IME its best stick to as few as possible though.

You could do worse than speaking to Shawspeed, BJP or Aldons.

Swindon Racing engines will sell you parts for a 2 litre engine based on the 1.7 block... don't expect change from less than £20K though...