when you said old i thought you mean the crossflow. the 1.3 HCS (high compression swirl) is still a new engine by my standards
the 1.3 HCS (or endura/ endura-e if you prefer) is a great engine if you want a reliable run about.
if the timing chain snaps the valves will hit the pistons. the chances of that happening are bascially zero unless the engine has done 200k, and even then its bloody slim. basically you never have to worry about it. ford do not recommend changing the chain ever, nor the tensioner.
you need to adjust the tappets regularly (takes 5 mins with a feeler gauge and ring spanner, change rocker gasket at same time, costs £2 for a new cork gasket)
keep an eye on the oil because they tend to burn it a lot. poor oil circulation can lead to camshaft lobe wear but that is only really an issue on badly serviced engines or if you dont keep an eye on the oil.
i abused a 1.3HCS escort from 70k to 125k and it never let me down once, it had a few boyracer owners prior to me. definately a more reliable and strong engine than anything else i've ever owned. crap power and torque, and not very fuel efficient, but that wasnt an issue at the time (just got license back after a ban).
tuning the 1.3HCS is a waste of time. the valves are tiny, you cant fit the 1.4 or 1.6 head, the only way to get it moving is to rip the fuel injection off and stick a carb on (from an earlier 1.4 CVH). it made mine a bit faster, but it still wasnt fast, it didnt like winters, and it cant pass an MOT like that. changing cams is pointless on the 1.3 HCS.
if you have the money, you can ask these guys to do miracles
http://www.specialisedengines.co.uk/hcs/
but as they told me at the time, its better to buy a faster car.