Cosworth of England built a twin cam 4-valve head to fit these engines, as well as beefier internals to go along with it (crank, rods and pistons) to put out somewhere in the neighborhood of 250 hp. Due to the 4-valve head's hemispherical combustion chamber, I believe you would need to install the special 4-valve-relief pistons along with the head at a minimum, provided you could even find an affordable head and the pistons over here.

When I was racing ministocks (around 1990) I found a company called BAT that carried high performance parts for the 2.0 and in their catalog they had the Cosworth kits. As I recall, the heads were $2K with about another $2k for the forged crank and other internals. I can't find them online, I don't know if they're not around any longer or just don't have a website...

Here's what the head looks like:





These are from an Ebay ad from England:

http://cgi.ebay.co.uk/2WD-Cosworth-H...QQcmdZViewItem

Price didn't seem bad at all, but of course you'd have shipping etc. to deal with. Could be a fun upgrade for the Pinto if you could get your hands on one over here. They're much more common in England.